In hospital for wisdom teeth removal do I get choice of gas or injection anaesthetic? Which is best and why?

With an injection don't you feel the stuff working its way up your arm and all around your body before you go to sleep? With gas, doesn't it smell unpleasant and does it take a long time to go under? Some of my college friends have had gas and hated it whilst others have really enjoyed it. Similarly with an IV - some friends have said it's the best way to be put to sleep because it's just like you've blinked your eyes shut before you open them again whilst others have said you feel really bad when you come round.