I would recommend HoMM3 and Eador. HoMM3 in my opinion is the best of the series, with HoMM5 taking the close second place (this one is not on sale though). I actually think that many people would prefer 5th over 3rd because of more modern look. This website
http://www.heroesofmightandmagic.com/ has a lot of fans maintained information about all games in the series and very useful.
Eador is a strange one. If you liked Conquest of Elysium, you probably will like this one too but it's not for every one. It has its fan base and fans swear by it. If you happen to read russian and comfortable with playing games in russian, you can play the game for free, but going to the
official site of the game and downloading the latest version (it says that it requires the key) and the latest patch (in which they not longer require the key). It was never officially announced that the russian version is free to play, however on the forums when people pointed out that you no longer need a key to play the latest patch the author of the game confirmed that this is no mistake. I would recommend to try a demo, but although there is a russian one, I can't find an english one alas.
