4870s are high ambient heat cards. Make sure airflow is healthy in your case.
I would go for the XFX based purely on the double lifetime warranty. Being able to sell it with a warranty increases resale value. That is why I picked my 4870x2 from XFX.
If you want to OC, the sapphire vapor-x is pretty brilliant (and quiet), but more expensive. I haven't seen any benches on the 4870 vapor-x 2gb, but in theory it could kick some high res ass. I have owned a reference cooler sapphire 4870 512mb, and it performed awesome, had it stable at 820/1000. It is sitting in a box waiting for my HTPC build to be ready for it.
Don't have much to say about HIS good or bad, never owned one of their products.