I just finished playing through the first game and had a blast. I highly recommend it!

What faction did you go for in your playthrough?

I started with HOMM2 back when it was new. Years later I played HOMM3 (a lot) and HOMM5 (a little). Now I've got the bundle too, and I'm starting with HOMM1 just because I wanted to see what the original game looked and played like.

I'm impressed! Yeah, the artwork is less appealing, and I miss the marketplace. But it's a fine game. And there's a lot to it: a campaign playable as four different factions, plus a long list of scenarios. If I try to play it all, I won't have time left in my life to get to the other games in the series.

So, start anywhere. I don't think it matters much. All the games have scenarios and settings that are friendly to beginners.

Just don't plan to play all of every game in the series unless you're very young and expect to have many, many hours of free time.

That's one of the glories of this series. You can start it when you're young and still be happily playing it decades later.

I said you can skip H4 and not miss anything HEROES-WISE. I will leave up to the individual to decide whether Heroes 4 is a good or great game in itself but it is not really a Heroes of Might and Magic game for the most part. It is as different from Heroes III as Warlords 4 is different from Heroes III.

EDIT: And without using the Equilibrius mod you have the problem that Heroes 4 had the worst AI imaginable. Even one of the developers visits a few message boards detailing why the AI was so bad and what happened that resulted in this travesty.