But I'm curious, as an AMD owner, were you satisfied? Are you looking to switch to Nvidia? Just checking to see what you're hoping to get out of your next purchase.
If I remember correctly, isn't Optimus only for laptops?
Anyway, like everyone else above I'd recommend the gtx 770.
I've always had a good experience with Nvidia and so I haven't warranted the need to switch over to AMD so I wouldn't know too much about AMD's cards.