Shloulet: Really not any particular learning curve for Might and Magic. In several it's very easy to level up, sometimes it's more difficult. I spent a while trying to figure out Might and Magic Book I: secrets of the inner sanctum, but I was able to dive right into Might and Magic VI
The earlier games are generally a little harder, especially one and two. Might and Magic III: Isles of Terra is where everyone recommends you start on the six-pack that GoG offers, but I've found Might and Magic VI is the easiest interface (fully 3d world) and the easiestr of the 3DO games (more flexible skills, more gimmes, as well as a larger game world than the rest of the games 3DO produced).
I don't know how that stacks up against your requirements, but it is a diverse series that's worth exploring.
One question ive been wondering though, how does your character fight with turnbased combat at once? Do you go through each character and get to see who did what damage or is it all at once? It wasnt really stated but id prefer getting to select each character.