I've beaten them all except MM1, MM2, and MM9. Congratulations on completing MM6!
I've beaten MM1-7. MM8-9 I've owned for years, but never gotten around to playing (I'm on my way through the whole series again now, though... so they're coming up).
I've also beaten HoMM1-2 campaigns. HoMM3 came out sometime before or after I was in college, so I was too busy to finish that one and unfortunately never returned to the campaigns (but played many a hot seat game).
I started Swords of Xeen once but I got frustrated with the difficulty and quit. I'm playing World of Xeen again right now, so this time I'm going to finish Swords.
Anyone have an opinion on Dark Messiah of Might & Magic? I found it on Amazon a couple weeks ago for $5 w/ free shipping, so I bought it.
DoMM won't feel like Might and Magic at all, but it's a fun action RPG. I enjoyed the way the environment was worked in as a weapon. There are a few tricks you can use in a pinch. Mainly those tricks involve kicking enemies into things (spikes, fires, off cliffs) but you can drop stuff on them as well.
I replayed DoMM recently. It seemed almost like it was intended to be more of a traditional RPG but the idea was dropped perhaps? Still, it's definitely enough game to have $5 worth of fun with.
MM8 is probably your best bet for enjoying a true Might and Magic experience. Letting characters begin with light and dark magic is WAY overpowered. You should enjoy it. There are also the dragons. For added difficulty, you should replay it using only one character. That can get pretty exciting.