since you're not doing 3D/CAD professionally, a gamer level card like GTX 670 or HD 7950 will be enough, you should focus on CPU for rendering and performance.
If you want the least possible trouble with linux i would say Radeon is the best to go with
My Budget for cpu+gpu+motherboard is around $ 1000
Which out of nvidia and ATI supports linux better ?
should I buy Workstation level graphic card ( like quadro and ATI firepro ) for my hobbyist 3ds work/CAD
or gamer level card will be enough for my needs ?
since you're not doing 3D/CAD professionally, a gamer level card like GTX 670 or HD 7950 will be enough, you should focus on CPU for rendering and performance.
If you want the least possible trouble with linux i would say Radeon is the best to go with