It would depend on whether you use the propitiatory drivers or the open-source ones
but I have found that nVidia's drivers to be less buggy than AMD's ATM that may change in the future but for your use I would recommend nVidia and if you use blender you get CUDA support for rendering.
Enjoy the Choice
my box:Q8200/Asus P5QDLX/8 Gb ram/WD 2Tb 2-500 G HD/GF GT640 2Gb Mint 17.2 Win 7 acer S243HL K222HQL
amd XP1800 on a asusA7N8x/ 789Mb ram/ sda 120 Gb ntfs sdb 80 Gb ext3 (fedora 10) gForce 6800 gt 128 Mb