Heroes of Might & Magic 3 Complete is to me, the best turn based fantasy game. I still play this game despite it being 3+ years old.
This set is hard to find in person, so you’ll likely have to order it online.
The set includes the orignal game, and both expansion packs. The expansion packs include the usual more maps and creatures and such, but the best feature is its random map feature, which isn’t included with the original game.
Some more Heroes 3 multi packs may have been released lately, so Heroes Complete might be outdated. But then again, the new releases are probably for Heroes 4.
Reading from reviews, Heroes 4 is cruddy compared to 3.
Heroes 4 adds polygon graphics at the expense of fluid gameplay and computer AI.
I strongly suggest Heroes 3 Complete. I was lucky to find mine used at EB for $20 Canadian. Didn’t include a manual, but they’re included as PDF files anyway.