I managed to beat MM1-9 and what a journey that was! :)
I'll definitely come back to MM3-7 again.

Edit: since it seems relevant, I also managed to beat:
- HoMM1
- HoMM2 + expansion (albeit I was a kid so I probably used cheats; might need to replay without the cheats at some point)
- HoMM3 + expansions
- HoMM Chronicles
- HoMM4 + expansions (also as a kid so I definitely used some cheats at some point)
- HoMM5 + expansions
- HoMM6 + DLCs/expansions
- Dark Messiah

I've beaten MM1-8, HoMM 1-3 with all expansions, Dark Messiah (not Disciples) of M&M.
Only MM9 was too tedious to finish, but I will make it another try some time.

Hmmm...that was a weird Freudian slip. I of course meant Dark Messiah.

How about Crusaders?

Haven't played it. And I don't think I've missed anything of value.

If you don't set your expectations high, it's not that bad. Platformer hack and slash.

It's actually pretty fun, the thing I like the most is some of the stuff is destructible and you can use it against your enemies.
I love getting them to fall off of walkways etc.