I'm not a series fan myself. I like GTA 3 and 4 the most and it's entirely down to tech novelty and in the context of my age at the time. I was 11 when 3 came out and 18 when 4 came out.
4 was my favourite at the time because of the game engine and car physics. 5 disappointed me because they neutered the cars and I didn't like the character hopping bank heist story that kept taking all my money away for story related reasons.
I've tried replaying 4 recently and got bored DNF'd so yeah idk if it holds up especially well.
Cut to present day and we got Rockstar who is a giga rich anti union corporation making a satire game about a country in which satire is dead. In a series they've not added a new game to since the PS3 generation because multiplayer became the golden goose. I don't have the highest hopes.