First Fave GTA - GTA 3. Hold the most nostalgia with that even though the improvements in Vice City and the culmination of all that good ps2 piff that made San Andreas should rank them above GTA 3....The music, the missions, the characters. Game's in my top ten of all time.
Second fave would have to be San Andreas for obvious reasons. I still think it's the most complete game in the series by itself edging out IV which I really enjoyed but had the weakest soundtrack in the entire series next to 5 and would only get a push in the runner up slot for the additions of Lost and the Damned and Ballad of Gay Tony which were way more interesting and had better music in my opinion. I was gonna pick Chinatown wars since despite being a handheld title was just and still is a goat tier travel game that's still in my rotation amongst Tetris Ds and Yoshi's Island.