gta: SA hands down is the best for me.

why?
1. the storyline. nothing can go wrong when you have Samuel L Jackson as one of your voice actor.

2. the concept. the game is HUGE. i did got sidetracked for MONTHS before continuing the story.

3. the soundtrack!! it's awesome! 90's gangsta rap, G-funk, alternative/rock. everything is in there.

plus i can buy properties in GTA:SA.
i know in VC also got, but seriously, i hate the 80's. too cheesy for me with all those Miami Vice reference. plus most 80's music sucks (except for metal and glam rock).

Niko might be badass, it's because he's that way (ex army + merc).