I read both of these in the last year and they're both phenomenal. I'm working my way through the classics, there's a reason they've survived centuries.
Actually, I listened to a dramatization of The Three Musketeers and I was struck by how _funny_ it is. The 4-way duel at the beginning is hilarious and Aramis' and Porthos' respective romantic escapades give great comic relief to what is otherwise an action packed adventure.
The Count of Monte Cristo is an investment, and the middle third drags, but it's necessary to set up the final third, which is so rewarding for the reader. It's the best tale of revenge and redemption I've ever read.