GTX 295 vs 9800 GX2 vs HD 5870



Depends on what you mean by better. The 295 is the fastest at dx10 and dx9, but it doesn't support dx11. the 5870 is the only one that supports dx11.

If I had to pick one, I would probably opt for the 5870 for under $400. That is if I could actually find one for sale.
 
Performance wise:
GX2 < 5870 < GTX295

However, 5870 = 1 GPU, GTX295 = 2 GPUs, so the price of 5870 is $100 cheaper,
so overall 5870 > GTX295

Then again, a 9800GX2 is the performance of 2 9800GTs in SLi, and costs around ~$140 on ebay...which is not too bad.
 
The 9800GX2 is about as powerful as a GTX 285, but I've heard of people having problems with them. The 5870 is almost as powerful as the GTX 295, but it uses a little less power and produces a little less heat. Its also alot cheaper so I dont see any reason not to get the 5870, except they're a bit hard to find right now.