haha... when I saw your subject, I thought of this:
http://www.engrish.com/leftovers/source/meltykiss.html
ok, now on a more serious note... I'd say the best kisses I've had are "physically" not much different from a mediocre or bad kiss... the thing that makes a kiss great, IMO, is really the person you're with. Do you really like that person? Does he/she excite you? Physically and otherwise? Because if not, the kiss isn't going to be all that great...