If you look at SOE's list of cards that work with EQ2, you'll find that they basically fall into two categories. That is, cards that were designed for DX8 and cards designed for DX9.
Cards designed for DX8 include the GF4200-4600, and ATI's 8500, 9000, and 92xx line of cards.
Cards designed for DX9 would be the Nvidia FX5800s, FX5xxx, and GeForce 6200-6800 series. For ATI, that would be the 96xx, 9700, 9800, and newer x600-x850 series cards.
The question of what's the best card for $200 is really debatable. The first thing though, I would rule out any cards that weren't designed to support DX9. I'd bet that within a year those DX8 cards flat out will not work with EQ2, in the same way that the old 3dfx cards that EQ1 was originally designed for are no longer supported.
If you check SOEs documentation, you'll find that they recommend you have at least a 256MB card if you want to use textures greater than medium quality. Unlike a lot of other games that are used for benchmarks, EQ2 uses a TON of textures, so I'd put 256MB on the must have list for EQ2.
DX9 support, 256MB, $200 to spend.
There is really only one card that stands out with those features, at that price, and it's a vanilla Radeon 9800 256MB.
The pro version has a faster clock, and for some of the effects it will be better, but the 256mb pro version is out of your price range. However, my experience is that the higher quality textures is what makes the game look good, and while you might have to turn down shadows and lights more with the vanilla 9800 you'll be able to run the higher textures with less memory thrash (ie, the 128mb version will be swapping textures in and out of main system RAM more often).
Anyway, thats my rec, GameVE has the 9800 256Meg for about $175 so the $200 price point can get it shipped to your door.
Other cards in this price range, 128MB 9800Pro, 256MB FX5700 and 128MB FX5900s, 256MB 9600XTs, will all work but probably won't work as well.
For about $70 more you can get a 6600GT 128MB, which is a new and much faster card that would almost certainly work much better in EQ2 than the 9800 256MB despite the smaller video memory. In the other cases (9800 pro etc) the speed difference is about 10-20%, not enough to negate the effects of the memory thrash, but the 6600GT is roughly 100% faster.