Elcs, what line of medium tanks would you recommend?
I'm already headed down the russian medium line (at the T34-85) and I could jump over from the german heavy line to somewhere in the medium line (tier 5 I think). I Unfortunately don't have anything in the US lines.
Lines of tanks are impossible to recommend. To do so would be to make sweeping generalisations about all of the tanks in the tree.
I found the US Meds to be most fun. Probably the most difficult to play and more team reliant. They have no armour but pack good guns, most of which have a good alpha and good RoF with adequate penetration. They are mainly hit and run tanks, useful for harrassing the enemy... but consider them dead/damaged if an enemy decides to fire at them.
German Mediums are a weird bunch but excel in sniping in the end. They tend to have a nice slab of sloped armour at the front which lends them well to plinking an occasional shot but are often susceptible to more module damage, especially the engine. It's a case of learning to feel of each tank and making it work for you.
Russian Mediums... my least favourite. The T-44 and T-54 look like hit and run tanks which can shrug off some crazy amounts of shells due to their slopings. The 100mm D10T will be your long time friend and it gets a bit stale, not great, not bad... but just boring. The T-54 is also often priority target number one and in a group of two or three, can really wreak havoc.
Personally, my Pershing usually rocks around in platoon with voice comms with a pair of T-54's. We do some great things but we're still stuck with hopeless teams at times.
If I had to do a tree again, I'd do the US every time.
That being said, knowing the stats of the M46 Patton, I am not excited for the changes... especially when the E-50 could be much scarier than the existing Panther II, which is also pretty scary as it is.