According to the article, at $200 the best cards for the money are the Radeon HD5830 and the GeForce GTX 460 768GB. The HD5770 is the best buy at ~$155.
If you want to compare to your current card, look at the last page of the article that includes a hierarchy chart with all modern GPU's. All cards mentioned so far are above the GTS 250 on the chart by 1 tier. According to the author, an upgrade is worthy if it is three tiers or greater, but that is their opinion. The HD5770 is on the same tier as the HD5830, so it may be worth it to you to save the some money.
I suggest you look at benchmarks of the games you like to play and determine if the HD5770, HD5830, or GTX 460 will give you what you need.
Palit have really stepped their game up lately, they are pretty good. If you live in the US they have a 2 year warranty now.
However you can find similiar brands within 15 dollars of that price range if you are uncomfortable with them. I just found you the cheapest 460 is all.
do you have a setup that is capable of running 2 gts250's in SLI? you should do that, unless you can afford a GTX460 1gb, then that would be worth it. If it was me, id wait for the radeon 6000 series, your current card is still fast enough for pretty much all games.