Why does all my friend agree that Nvidia is much better than ATI?

its because Nvidia supports more games and provides more superior graphics that ATI does..but that doesnt meant ATI is bad..but its just that nvidia is better than ATI..and ive also heard that the ATI graphic card become more hot after a prolonged use..plus the nvidia geforce option is really powerful as well

I think it's because ATI have some not too great products (obliousy, other ones are very cool) like the ATI Radeon X1600 Pro, that works fine, but it overheats and need a lot of energy.

If that's the case, probably they experienced best quality for gaming using nvidia, because for what i know nvidia supports almost all the latest games now available at the market..