I like Lampley overall, although I think he consistently shows bias in favor of specific fighters, notably De La Hoya and Barrera.
Merchant was once a great analyst, now you're lucky to get one or two sentences out of him in between rounds. He's still worth having around just for the unintentional comedy.
I think Steward does a very good job. I always thought Foreman had no clue what he was talking about.

Fran Charles is beyond horrible.
I like Kellerman, sometimes his voice can kinda get to me because he yells more than talks. But overall he does a good job, he was great on ESPN FNF, and I assume he's being groomed to take Merchant's spot someday.
I don't think Lennox is anything special. Like someone said earlier, he just states the obvious most of the time. But I think they should keep him around, he certainly sounds like a bright guy, he could improve if he gets more comfortable.
I've always thought Brian Kenny would be a great addition to the HBO team, it would be great to see him take Fran Charles' spot, but I assume as long as he's at ESPN that's not going to happen.