You're asking for too much, if you want it with ease

ATI cards can well do that too, with the same effort.
ATI cards don't suck, it's only a grief that the drivers are a bit difficult to install, but usually don't take long to get working. I've found out the same problems do exist with nVidia's and all other cards, not just ATI. It's easy to find an nVidia card that does not work in Linux, just as easy as finding an ATI one or of any other manufacturers.
I suggest you buy a relatively new, but not the very newest, since then you'll probably have the greatest chances of having a card that already has a driver support for Linux plus some real power compared to nowaday's computers and demands.