Where did the OP say he was on a tight budget ?
Actually that is a point, I was looking at the list of what he's got now, and thought to myself that it's a build that looks budget constrained.
I'm still a bit torn because I tend to feel the height sweet spot is a bit north of 1080 pixels, and a 2560x1080 feels to me like a 2560x1440 with the top shaved off. If a 2560x1440 were available in the same price range I'd be wanting to look at that, but I do feel the wider screen is noticeably more useful if it's only 2560x1080 vs 1920x1080.
Ah yes, just like workflow determined the aspect ratio to be 4:3, then 5:4 and 16:10 finally though not permanently settling on 16 by 9. [/irony]
Honestly at this point the best aspect ratio for my taste would be one that doesn't change. Could it be that, people who feel discomfort going from one screen to the other somehow blame any of the two displays, instead of the actual culprit - change though forced sideways "innovation"?
Funnily I'm speaking from my personal experience, and my workflow means that 21:9 is a vastly superior option to 16:10 or 16:9 at the resolution I'm discussing. Honestly the optimum for width and height is determined by different criteria. For height, it's an information criterion. Anything short of 900 or so pixels feels constricted and short. ~1000 is about the point where I'd rather be able to stack two things side by side rather than go taller because there's a comfortable amount of information vertically. Generally though I want to be able to have one major task that's wide (fullscreen browser, game, IDE with side menus and two pieces of code, etc.), and one secondary thing that's usually pretty narrow side by side or three narrow tasks, so up through here I pretty much demand two monitors. But by the time I get past probably 1200 pixels (not sure, my experience is with 2x1920x1080, 2x2560x1440 and 3440x1440), there's enough vertical space that I'm well into the land of diminishing returns, and wouldn't gain much actual real usability gains (and see some downsides from the distance between top and bottom of the screen) until probably 1800 tall screens and more likely 2k tall screens (and this at a pixel pitch of around current 27" 1440p screens, past that contributes sharpness but not information because I have to start making things bigger). That's a pretty serious height and I'm not sure it's really 100% something I'd be able to manage without a bit of work and a nice software suite (and potentially a 2 dimensional curved screen).
And interestingly I don't feel discomfort going to new screens. I feel great. What I do feel discomfort with is going back because the old configuration downright sucks in comparison. Two 27" 1440s is ungainly and awkward, while one 34" 1440 with software to break the screen up into arbitrarily sized chunks for programs is wide enough to do a much better job of doing nearly as much, and that nearly as much is enough that 95% of the time, it's doing everything I need brilliantly rather than 97% of the time doing what I need decently.