Heroes of Might and Magic IV
I played it with my best friend for years, we both agreed it was superior to III.
Later I heard people think it svcks.
My vote also goes to Heroes of Might and Magic IV. Honestly as a HoM&M fan I really loved HoM&M III and I liked HoM&M IV too. I find it strange that most people seem to point towards disliking the hero system on the battlefield in HoM&M IV but I find it to add flavor and it creates another things to watch out for when you're in combat, you can't just rush your creatures out, you have to be tactful and protect your hero, which does make a lot of sense, war-leaders aren't immune to damage until all of their troops have been killed after all. The thing I would rather expect people to complain about HoM&M IV with is that the Campaigns become really easy if you allow your hero to level a lot, I remember when I started the first one which is the Stronghold one I had to try the first part of the scenario a few times before I managed to finish it because it was quite challenging, the next part was a little bit easier as my hero was more powerful so I could use it for combat properly, but by the time I hit the last part of the scenario I just ignored my castle and stormed the entire map with my hero alone slaying anything in my path including fully fledged enemy heroes with my hero alone...
So yes the Campaigns of Heroes of Might and Magic IV were really easy because of that but the individual scenarios you could play were good because you of course started with your hero at level 1 and when you played online (or just when you played multiplayer with a friend) then your hero would be countered by the enemy players heroes. And that created even more room for deciding on tactics, like do I take out a group of Titans first since no one likes a strong hit from a Titan, or do I neutralize the enemy hero who could quite possibly mess up my entire game ? And also it brings up the question "How do I protect my own hero in combat ?".
I however really hate HoM&M V. I'm not all that pissed about them changing the hero system back to the old one since a lot of people really didn't like the change from the 3rd game, but I really hated the amount of random variables introduced into combat in that game. Too many creatures have abilities like "50% chance not to hit this creature." When you can do the same battle in a strategy game twice, winning one time and losing the other, then that is a sign that the strategy game is bad. A strategy game should be about how good you are at coming up with a strategy to fight your opponents troops, not about how lucky you are. Imagine if in chess every time you tried to take out a piece of your enemies troops, if you then had to flip a coin and if you lost the flip then it wouldn't be his chess piece that dies but yours. That's what Heroes of Might and Magic V is like.
I realize to an extent there are factors of luck in HoM&M IV too, however those are very minor in comparison and were the same in the 3rd game. In HoM&M IV if you do a fight exactly the same way twice then the outcome will be the same at least a good 99% of the time, not only a few times if ever like in the 5th game.
So yeah, Heroes of Might and Magic IV was better than most say it was, I'd even argue it could out perform III and it most definitely is better than V.