In the 200+ price range the new ATI cards are generally more competitive from a value standpoint--its hard to find a price for performance contest that Nvidia wins here at the moment.
Your choice of whether to go with 5770s, 5850 or 5870 should depend on what kind of monitor resolution you are planning to push out with the card as well as how much you care about the bragging rights of having a beast of a card. Unless you are an extreme gamer you probably dont need the 58xx series, but if you have the money to spend why not do it?
Here's the "winners" from THG's latest (December) GFX Roundup Best Graphics Cards For The Money: December '09
$50 - HD 4650
$65 - HD 4670 / 9600 GSO
$85 - 9600 GT
$95 - 9600 GT / HD 4830
$110 - GTS 250 512 MB
$120 - GTS 250 1 GB
$155 - HD 5770 / GTX 260
$200 - HD 4890 $240 - 2 x GTS 250
$310 - No winner (HD 5850 Honorable Mention) $330 - 2 x GTX 260 / 2 x HD 5770
$400 - 2 x HD 4890
$410 - No winner (HD 5870 Honorable Mention)
$465 - No winner (GTX 295 Honorable Mention)
$625 - No winner (HD 5970 Honorable Mention)
Note that the ATI 5xxx series wins only 2 of the 15 categories, both with the 5770. ATI 4xx wins 5, leaving nVidia w/ 8. Coupls of qualifiers tho:
1. The above is based, if you read the whole article, on the assumption that DX11 is a non issue "today" considering the THG audience generally upgrades quite frequently. The author advises that if you are going to keep your card a number of years, say till fall 2011, safest bet is to future proof your investment and get an ATI 5xx series. If DX11 is to be the "next big thing" you can be sure game devs will be wanting to strut their stuff for before XMas shopping season begins.
2. If PhysX intrigues you, then that would be another reason to sway your decision. read the links below to see if it tickles your fancy.