I think Inferno, Dust 2, and Season would be my favorites because their layouts best fit my aggressive and passive playstyles depending on the situation in the game I'm in.
Nuke is always fun for intense strats and hardcore raging on Terrorist side.
Mirage is pretty fun too.
Cobblestone is probably my least favorite, but I've slowly started disliking the layout of Cache the more and more I play it.
The main competitive maps are my favorite and that is because of how dynamic they are: cache, mirage, inferno, D2, nuke, and the new train. Not sure why nobody likes it, it's a killer map to be playing on regardless of team.