Whats the most important features of a video card?
Pixel pipes and clock speed must be considered together.
Fill rate is probably more appropriate, as a 24 pipe card @ 400MHz vs a 16 pipe card at 700MHz, I'd rather have the 16 piper, and it will likely be faster.
Mem interface > mem speed.
Mem type as mentioned is not really even worth considering when you can look at speed (which is more important, although can be influenced by type).
CPU: Q3570K @ 4.1GHz 1.23v // Mobo: Asus P8Z77-V // GFX: Sapphire Tri-X 290 @ 1000/5200 // RAM: Corsair DDR3 @ 1600MHz 9-9-9-24 // SSD: Samsung 830 128GB
Video cards: TNT2, Ti4400, 9800, 7800GT(+7200GS), HD4850(+HD2400), HD6850, HD7950 (Laptops: GF6150, HD3200, GMA500)