The MM3 game engine by now is antique, but my personal opinion is that in terms of the puzzles and game-play, this was the best of the Might & Magic series.

MM4 and MM5 (a.k.a. World of Xeen) should be played together, because when the two games are on the same logical drive, they interact to form a small third game. MM4 is a bit boring in places, but as soon as you win the final battle and defeat the villainous Lord Xeen, the "Moons become aligned" and some portals giving your party access to MM5 become active. MM5 is a better game than MM4, IMO. In the course of playing MM4, you will find a series of dungeons that you cannot enter, and keys for which you cannot find locks. The keys enable you to enter some dungeons in MM5, and, not unexpectedly, you find keys in MM5 that open the locked dungeons in MM4. These dungeons, some of which are pretty stiff, constitute the small third game. Together, MM4/MM5/WoX forms an enormous game that is well worth playing.

Big Daddy Jim (and his team) created mods of MM7 and MM6, neither of which I have played, but both were highly recommended by people whose judgement I respect. The mod of MM6 actually amounts to a new game. It uses the same territory as MM6, but everything else has changed - the game is called The Chaos Conspiracy.

Thank you for your replies. I am now certain that I want to play MM3 to MM5 first, and then the mods.

Do you know if the mods will work with the GOG versions of MM6 and MM7?

Now that I think about it I have played some mod of MM7 that has only the light path, but also gave master dark magic near the end. Is this the same mod you mentioned?

Thanks again