I think they usually write Michael pretty poorly. (Like, we never get why Hunter would want to stay with him... all he does is bitch and whine like a less funny version of Debbie).

But when they write Michael well, I love him. I love that scene in S1 where he and Brian are "broken up" and Brian is trying to hang out with Ted, but keeps fantasizing about what Michael would say if he was there instead of Ted. That sort of sweet/innocent/infectiously enthusiastic side of Michael really appeals to me, and brings out a side of Brian that I like.