I need monitor advice

I bit of background. I mainly do web development, and a little gaming, (WoW, Overwatch, MTGA, and ESO right now). I've currently got a pair Asus VS239H monitors running off a 1050ti. These have been fine for the last 7 years, but I'm building my daughter her first PC, and my wife's 15 year old BenQ finally gave up the ghost, so I was thinking I'd upgrade myself to a larger 4k or 3440 x 1440, and distribute the Asus monitors between them.

Basically, I want the most screen I can drive with my 1050ti. I've been wanting to upgrade to a 4k for a while, but with the prevalence of the ultra-wide monitors, I was thinking that that may be a better option. Though less pixels, the shorter form factor would mean I could mount a smaller secondary HD monitor above it later for ancillary tasks, like RDP.

With all of the brands, and specs I'm not sure what I'm looking for. What brands are crap, and when I'm paying for a brand name, instead of features. My budget is about $650, total, so if I can get a good monitor for that, cool. If I need to upgrade my video card to something like a Radeon RX 570, that's cool too, but I'd be looking at a cheaper monitor at that point.

Any advice is appreciated.