I can't pick a favorite
The male trinity is Jack, Desmond, Hurley
The female trinity is Kate, Sun, Juliette.

But all the characters are amazing. LOST is probably the only show with such relatable and likable characters. Truly a brilliant cast and amazing characters, even if there are so many. They all get to shine individually.
The only character i always hated was Michael. Him and Walt were the most annoying and irrelevant characters of the show

I'm currently re-watching the 1st season for like, the 20th time, and i always skip Michael and Walt's scene. They are so unnecessary and annoying. Michael has done one bad thing after another. Killed Anna Lucia and Libby then turned on his whole group and exchanged them for a way out.

I don't even care if he tried to redeem himself. He's a piece of ****.

I was so done when they brought him back.... it was unnecessary both times they did it in season 4 and 6