So I'm posting this to ask if any of you gerbils have a better suggestion. I just can't figure out video cards with all the rebadging that's going on. Thanks!
I'm confused. You "just upgraded" to a R7 250 but you're asking if we have a better suggestion? If you're okay with returning or repurposing the R7 250 and buying something else, then you should definitely do that because XCOM is a cracking game, possibly the only single-player game in recent memory that has kept me indoors for 48 hours straight.
For a 24" monitor (assuming it's 1080p or 1200p) the sweet spot both in terms of performance/$ and performance/Watt is going to be a 2GB GTX 950 for about $150; AMD has nothing
sensible to compete as they're re-using the woefully outdated Pitcairn chip from the 7850 still. Not only is it low performance/Watt - it's also lacking in some useful features and support for current technologies.
If you have a little more cash, the 4GB 380, 380X or 960 are decent options for a smidge over $200 but unless you start playing intensive, current-gen AAA titles at ultra settings you won't really see any difference. They'll also need 2x6-pin power connectors at least, don't know what PSU you ended up with but I'd be suggesting a decent 450W at least for the 380 variants.
Likewise, if you have a little less cash, the lowest point of entry is the R7 360 that JAE suggested, but it's outside the sweet spot - meaning that you'll get lower performance/$ than you would if you spent another 50-60 bucks on a GTX 950.
As for the fuzzy output using D-Sub, that could be anything; D-Sub outputs tends to get ignored by manufacturers these days so the quality is a bit of a crapshoot. As rules of thumb:
If the D-Sub connector on the backplate is connected by a short internal cable to the card, try to switch your connections around so that you're using a DVI port on the back of the card through a little platic adapter block.
Check you are using a decent-quality VGA cable, not a super-cheap thin one
Make sure your VGA cable is as short as you can get away with, and that it's not running alongside other high-noise cables like a bundle of AC mains cables or wall-wart converters.