I've Never Played San Adreas Before so I guess Vice City is Better. but I'll Try to look into it if I have a time maybe I'm wrong.
I think that Vice City had a better storyline, but I am partial to San Andreas because I'm from California. So, San Andreas gets my vote. I love all the GTA games though! They are among the very few that I will replay even years later.
san andreas is much better as it has better graphics and the cheats are better, also you get to fly good aeroplanes and you can get jetpacks and theres a cheat for a parachute, what beats that!