Then in university, I discovered Wake of Gods [1]. This was a fan-made extension of the game that fixed some stuff ( like Eagle Eye being useful, fishing for artifacts in mana well's, having commanders ala heroes 4, having a bank from which you can loan money, etc.).
I play heroes 3 complete edition with HD Mod [2] to this day, a pretty awesome game, and still has an excellent, thriving community.
Honorable mentions besides Heroes of Might and Magic 3 - Heroes of Might and Magic 4 (with all expansions) and Heroes of Might and Magic 5 (all expansions - Tribes of the east). Heroes 5 is the closest to Heroes 3 as mechanics and gameplay, and I enjoyed it a lot.
To this day I play roughly 4-5 games: Dota 2, Civilization 5, Baldur's Gate 1&2 EE and Heroes 3.
[1] - http://heroes3wog.net/