OK, but the way you wrote it wasn't about the expense, you said the a6000 was good but saddled with mediocre lenses, not overpriced lenses. I said dismissing E-mount lenses as mediocre is incomplete at best and wrong for shorter focal lengths.
However, if you're amending your statement to take expense into account, I would agree for telephotos and disagree for wideangle to normal/short tele.
- The 50/1.8 OSS is $300, or about $70 more than the Nikon 50/1.8G. On the other hand, the Nikon doesn't have stabilization, the Sony regularly goes on sale for $250 (or even $200 when bought with camera), and the Sony might be a little sharper in the center wide open. The Sony also has better bokeh--this isn't even a contest. If you factor everything together I think the Sony might actually be better value for the money despite higher sticker price.
- The 35/1.8 OSS is reasonably sharp even wide open, and stabilized, but the Nikon 35/1.8G DX is basically about as good but with worse bokeh and no image stabilization. Still, the ~$200-250 price (depending on sales) difference may be hard to swallow for many people. I think the Nikon is better value but it's not as huge of a margin when you factor everything in.
- The Sigma 19/30/60 are great, sharp, good bokeh on the 60 and can be found cheap or on sale often. They are great if you don't mind f/2.8.
- The Sony 10-18 is a constant f/4 and reasonably sharp; its Nikon counterpart is 10-24, slower, not constant aperture. The 10-18 can also work on full frame with a little tweaking, at most focal lengths. I'd say the Sony is at least equally good bang for the buck as the Nikon.
- The ~$350-400 Samyang 12/2 is a minor miracle for astrophotography and not bad for everything else. It's manual focus but cheap and light for its focal length and aperture. Nikon doesn't have anything like it. The closest you get is a big, heavy Tokina 11-16/2.8.
- Similarly the 85/1.4 Samyang is MF but for portraits to get sharp eyes you might want to MF anyway. Nikon doesn't have anything priced like it. And the F-mount version of the 85/1.4 is not very usable with DSLR OVF because of inability to "zoom in" to get fine-tuned focus. Nikon only wins if you need fast autofocus. If you are ok with MF then Sony's got the better value. And if you are ok with slower AF, a Canon 85/1.8 + adapter costs about as much as the Nikon and while it's not as sharp wide open, it gets quite good stopped down. Plus much of the time for portraits you don't want to get TOO sharp anyway.
As I implied earlier, Sony suffers on the long end; their stuff is either not great or overpriced or both, ranging from the 55-210 to the hilariously badly priced 16-70Z to the underwhelming 18-200. The 18-105 is actually not too bad for a constant f/4 lens, and reasonably sharp, but with some distortion that negates the f/4 for some video work, and it doesn't go to 16mm like the Nikon 16-85 so it's perhaps the "least bad" longer-tele option for E-mount.
As for shorter focal lengths, read above for examples of great values like the Samyang 12/2. Yes the 20/2.8 and Zeiss 24/1.8 are both overpriced for what you get, but the Sigma 19/2.8 is a LOT cheaper and still very good; you seem to have forgotten about it when you picked on the Zeiss 24/1.8. There's a FE 28/2 coming out early next year that may be priced more reasonably while delivering good performance, as an alternative to the Zeiss.
But Nikon has a bunch of overpriced lenses as well, like the 17-55 and 70-300 VR. They aren't bad, just overpriced relative to alternatives like the Sigma 17-50 OS and Tamron 70-300 VC. The Nikon 55-200 isn't any better than the Sony E 55-210. And have you seen the prices Nikon is charging for lenses like the 20/1.8G?
Furthermore, as you touched on, you can adapt most lenses to E-mount. Sometimes with CDAF, like Canon EF/EF-S lenses. You can also use cheap MF-only legacy glass with easy focus peaking and zooming in on EVF, something that you can't do on DSLR. Can you use legacy Zeiss on Nikon F? No. How about cheap but good Canon FDn? No. Can you use speed booster adapter on Nikon F? No.
So as a recap: Sony's E mount is far from complete. As it stands they could use better telephoto lens options. A 90/2 macro (supposedly coming next year but at a sky high price, and ditto with the rumored 85/1.8. Longer or larger-aperture (f/2.8) telephoto zooms are nonexistent right now.
But E-mount actually looks pretty good for anything up to 50mm or so. The 28/2 is coming as an alternative to the Zeiss 24/1.8--and let's not pretend like Nikon has such great value with its 20/1.8G either. (If the FE 28/2 sucks or is overpriced I will agree that a hole remains.) Samyang owns the ultrawide/fisheye segment, especially the 12/2, and the Sony ultrawide zoom isn't any worse of a deal than the Nikon ultrawide zoom (see above). The cheap Sigma E-mount f/2.8s are good value if you can tolerate f/2.8. The 50/1.8 OSS is better bang for the buck than the Nikon 50/1.8G in my book (see above). And the 35/1.8 OSS might be worse value than the Nikon, but at least you get good bokeh and stabilization.
The Sigma f/1.8 zoom you mentioned, by the way... look at its price and bokeh and size and weight. Sharpness isn't everything. I would rather shoot with primes.
And as for 24 vs 30mm I think that's just a little too much difference in focal length. That's like comparing 36mm vs 45mm, so a Sigma 30 for Nikon isn't exactly in the same classification as the Zeiss 24.
The other lenses you touted are longer, and as I said, I was not talking about long teles. Sony still needs to work on those for E/FE.
For the reasons above, I am reasonably happy with my Sony E system for anything up to 50mm. I am waiting for a good 55-300 or 70-300 f/4-5.6 from Sigma or Sony, but luckily I don't shoot those focal lengths as often, and usually for portraits in which case I have an 85/1.8 I can adapt anyway (I don't mind MF for portraits). For those with deep pockets, I would not recommend EITHER Sony E or Nikon F for APS-C-or-smaller telephoto. I'd recommend the Panasonic FZ1000 (budget option.. smaller sensor but nice bright lens and good zoom range) or Canon 7DII and Canon telephotos, instead. (Or 70D if you just need reach but not faster/better AF and bigger buffer.) Nikon just doesn't care about DX; their USA marketing guy literally told DPR in an interview that he wants to tell Nikon shooters to buy an FX camera.
https://www.youtube.com/watch?v=USVwCubpq9I&feature=youtu.be&t=14m44s I mean wtf. How about no, because I don't need an FX camera and the cost, size, and weight that result, and as sensors keep improving, I'll get better image quality at any given ISO over time ANYWAY? I mean, today's APS-C cameras can give you everything that FX cameras gave you 7 years ago except thinner DOF, which I don't really care about and is overrated. Look at the Samsung NX1 as an example of what a high end APS-C camera can do if companies didn't artificially cripple their smaller sensor offerings in an effort to get them to "upgrade" to larger systems that they may or may not want.
Nikon so very clearly doesn't give a damn about its DX users. I didn't leave Nikon. Nikon left me and the other DX shooters it doesn't give a damn about except as potential feeders into FX.
But my shooting needs may not be yours, and I understand and respect that... I did say that I thought well of Sony E-mount's wider lens options, not their longer lens options! And worse come to worst, I can simply buy a FZ1000 instead of a longer E-mount lens, so I wouldn't even necessarily miss out much on the longer Nikon DSLR lens options.
I don't think cherry picking lenses that buck the trend proves much of anything. The trend remains that when you pay the same amount of money for an E-mount lens, you get something smaller and lighter but of lesser image quality than, say, a Nikon Dx lens or a Sony SAL lens. It's just how that market works; give up some weight and you give up some IC in conjunction - not a free lunch, but a trade-off. But the big problem with the e-mount line is that larger options simply tend not to be made available, so the trade-off is forced on you. Maybe if you use adapters you're OK, but those add to weight and cost and probably affect the results you get negatively, mess with your autofocus, etc.
If you look at Nikon Dx lenses that punch above their weight you find things that again make the E-mount top rung look weak by comparison, for example:
Sigma 18-35mm f/1.8 - I don't think there is a single e-mount zoom lens with this a wide an aperture, let alone one at such an important focal range. The aperture is also constant.
Sigma 50-150mm f/2.8 OS - the top focal length of this lens is close to the e-mount line's maximum and to get a similar aperture you'd have to pay thousands. I think this one's $800. There's a lighter and cheaper non OS version too.
Nikon 18-300mm - you have two options here, a faster and slightly sharper version and a very light one; no matter which you pick they blow both e-mount superzooms and telephoto zooms out of the water
Now, the weakness of a lot of these lenses is that they are large, which has been my point all along.
It's interesting that you mention short focal lenghts as a counterexample because the wide end is exactly where I feel like the e-mount series' options are lacking. Going by your examples, you seem to mean something closer to medium angle. The 35mm f/1.8 lens is already +/- 50mm in full frame terms, which is well past the 35mm that is typically considered a "normal" angle.
The closest thing to a sharp, fast wide angle lens with auto-focus is the Carl Zeiss 24mm f/1.8. It's expensive, it's not *very* wide, it's fast but not especially so and it's sharpness at fully opened aperture is sub-optimal. That's the best you can get with e-mount when it comes to this crucial focal length range. Of course, it's big asset is that it's small. But the larger/heavier option is simply not there. An equivalent Nikon Dx Sigma lens is 30mm, f/1.4, only $400 and probably sharper.
So instead you're stuck with the cheap Sigma f/2.8 option, or the non-auto-focus 24mm Samyang, which is heavy and un-sharp at maximum aperture. For my purposes, it didn't do.
I probably express myself stronger than I should in these posts so please accept my mea culpa on that. I write these posts in a hurry and its hard to get nuance across when you write in quick concluding sentences. I really don't think we see this very differently when it comes down to it. I liked a lot about the A6000 and the main reason I'm a happy switcher from it is because the D5300 ticks so many boxes on my wish list. Had it not been an option, I'd probably still be using the Sony.