I would definitely agree with Albin from La Cage, Sweeney is pretty challenging (although as a tenor, there's really no hope for me to ever play him...just a personal note, not saying that that doesn't mean it's not an amazing role).
I definitely do NOT agree with Harold Hill and ESPECIALLY not Billy Bigelow. Iconic characters, yes. Difficult? Not particularly. I know I'll get attacked for this one, but I recently saw Carousel live for the first time, and when I was coming in from intermission I looked at the sign that said there would be gunshots in the show and hoped they would be directed at me...
I think it's very difficult to name a male character that goes on the same journey as Rose. I think the main problem is that the emotions that Rose goes through are very much related to her maternal relationship with her daughter, so it's difficult to match that. It's a little disappointing as a male actor that there really isn't a part to play "before you're gone", but who knows what the future holds?
I should also mention that while a beefy dramatic part is to be envied, comedic roles are nothing to be scoffed at... as a matter of fact, I rather prefer them.
I hold a degree in Musical Theatre from Montclair State University. It is useless. Now I'm funny for money. Oh, and I sing.