Past $200, the launch of the GTX 900 series has caused a major disruption of pricing and sweet spots. Between the $189 R9 280 and $279 R9 290 there are some cards such as the R9 285 and GTX 770, but none of them are very interesting nor make all that much sense right now. With the R9 290 at $279, your best bet after the $200 mark is to just keep on going until you reach the first of our high performance cards.
At $300 or less theres really no choice here. To that end AMD essentially wins by default, but the real winner is gamers who are getting a good card at a great price. Based on the second-tier version of AMDs flagship Hawaii GPU, the R9 290 packs enough performance to tackle 1440p at medium-to-high settings, and its 4GB of VRAM means that it should have no problem even with demanding cross-platform games. Alternatively, if you want to drive 120Hz without spending a fortune, the R9 290 should get you there.