After playing GTA V for 3 months, I can honestly say that there is no one character that stands out or a character that I could class as my favourite.
The characters just werent memorable IMO
I like Jimmy because he reminds me of certain people I know IRL, Lamar also had his funny moments and I thought Devin Westons assistant Molly was a good character, mainly because she was a female character in a position of some sort of power, which made a change.
Other than that, for me there was no one character that I was drawn to.
In terms of the protagonists...
Michael - During the story I really liked Michael, especially early on in the game when we're first introduced to him. But after playing the game for 3 months he's probably the most boring out of the 3. I've played as him the least.
Franklin - I just look at Franklin as under developed. I feel they could have done much more with him...but didnt. I hate how he just turns into some hermit living in the hills. He is the loneliest character in GTA history. Some of his dialogue is quite cringe as well, especially when the dialogue between hi and white characters is about him being black or being from the ghetto, so cliche and generic. But weirdly, having said all of that I still kinda like him.
Trevor - I actually like Trevor, I'm not one of those weirdo fan boys that goes on like he's the best character ever and I'm also not a fan of his OTT violent/hell raising persona, all a bit too much for me. I actually HATED him when we were first introduced to him. But after a while he's really grown on me, i find travelling around Blaine County more fun when i play as T for some reason. Not to mention I love how the war with The Lost carries on even after you've done missions against them. On site gunplay everytime they see each other, which is quite immersive. With Franklin this same kinda thing shoulda happened with Ballas after certain missions, but it doesnt for some reason. But yeah Trevors cool and the most interesting out of the 3 IMO.
But even so I think all the protagonists were fairly weak in comparison to those that came before them.