I really dont want to leave Nvidia. You've got to convince me. Whats better about this ATI card.
Here's the reality. If you don't want to leave Nvidia then go for a GTX 660ti or a 660. We've given you the benchmarks, gave you answers and have talked about the better side of GPUs this generation.
If you don't want a AMD GPU, then by all means, go the Nvidia route and be happy.