DM is a great game, but an M&M game in name only, and a different genre.

VI already had free movement. And honestly, I like that the best. I hate how all newer dungeon crawlers have downgraded back to the grid based movement again.

For MM:

I skipped 1-2 as I didn't want to play stickman graphics. They are of one style.
I played 3-5 and loved the art style. IIRC 4 is the first game I ever played where we got a base. 3-5 were an upgrade from 1-2.
I played 6-8, which were the next upgrade. IMO 6 is the best, and 7 is good. 8 suffered budget cuts and isn't completely finished. 8 also forced you to have a monster party instead of standard peeps, so you may love or hate that.
9 is an abomination. It's its own style as this was the end of 3do and new world computing. The world is empty, the setting bland... the only thing I liked was the class promotion system. Otherwise, gamers pretend MM9 doesn't exist like people pretend Ultima 9 doesn't exist.

For HoMM:

1 is crude, 2 is fun but a bit unbalanced. Art style is the same as MM3, which I loved. 3 adds more to the towns and balances and fleshes things out more. H3 also has the largest modder attention I believe, with first WOG and now Era. There are tons of maps for H3 and that's what I would suggest. You could always try the H2 demo if you wanted, which is what sucked me in to the HoMM games in the first place.
I've never played 4+

Dark Messiah was a HUGE disappointment for me. When the companies went under, Ubisoft paid millions for the MM brand. They slapped it on Dark Messiah when it really has NOTHING to do with the MM games, not in style, setting, tone, or anything. The MMs are rpgs, the HoMMs are strategy. DM is an action adventure. I bought DM based on it being "of might and magic", and felt betrayed to learn it was just a marketing trick. I've been pissed at Ubi ever since.

So for MMs I suggest MM6, and for HoMMs I suggest H3. As always, I suggest watching lets plays to get a feel for gameplay.

Might and Magic: Clash of Heroes

(just throwing an oddball choice out there)

I have that game around somewhere (Nintendo DS version), but never got around to opening it.
MM1 is the only one that requires graph paper (unless you want to attempt it mapless); even MM2 has an automap.

Xeen really plays like MM3, but mins the hirelings, minus druids being unique, and with some money issues that come up later game. MM3 may be a huge leap from MM2, but Xeen is not a huge leap from MM3.

Regarding HoM&M series - despite popular opinion, Heroes 4 is not bad for the first contact with the series. It's true that it's quite different from the model present in 1-3, but it has many things good for the beginning:

- proper in-game tutorial (in opposite to "print yourself this paper and do what it says on one map" in Heroes 3)
- plenty of important improvements which are making game more fluent and with fixed some tedious elements (caravan system+increasing new creatures daily allowing to avoid indefinite returning to your castle, prison system preventing AI from notorious cheating present in Heroes 3)
- story is in theory continuing plot from Shadow of Death, but in practice all stories are working well independently...
-not to mention that stories and campaigns in Heroes IV are much more interesting than those in Heroes III

Still, if someone wishes first to have first contact with more "classic" approach in the series, I would recommend... Heroes 2. First game is a bit... weird to play and has almost zero plot. Second is imo good to check if you like this kind of game or not. Plus it has incredible charm, something I was missing a bit in third game.

It is "of might and magic" because the setting is the world of Heroes of Might & Magic V (which they made before that) and it actually serves as an ending to the entire story. It was a nice attempt at something else. Definitely better than Crusaders.

MM6 was the first one I started with, and I really enjoyed it. Though I've never been able to really make good progress in that one. It does have some great secrets to find, however.

MM7 I've nearly finished multiple times, It feels the most polished of the 6-8 engine games in my opinion. I especially like using the grayface patch to enable mouse look mode (more modern control scheme), as well as running the game in XP SP2 compatibility so that you can use the hardware rendering engine (Not enabled by default in the GOG install).

MM8 does indeed feel like they ran out of time for it. Still quite fun though.

Recently started a MM4+5 play through and the animated style graphics have aged very well in my opinion. Also has a great MIDI soundtrack when configured to use General MIDI or the SC-55. (MT-32 seems to cause random freezing for some reason)

For Might and Magic 1-5 I recommend to check out the tool "Where Are We?":

www.eskimo.com/~edv/lockscroll/WhereAreWe

M&M 1-5 are more accessible with it.

Disciples 2
(yep)

I think they were a downgrade in some areas, like itemization, difficulty and especially combat, so I for one prefer the older ones.
Otherwise I agree with your post.

These games have interesting lore and related plots. Same world, same characters.
MM1-5 ->...-> HMM1 -> [ (HMM2 -> MM6) -> (HMM3 + MM7) -> MM8 ]

Maybe HMM2 is too old but i remember it was great. And it began "modern" history in the world of Enroth. MM1-5 - are like ancient history of world creation.
ED: In-game history. i am not talking about games engine or how old they are.

Characters in later games with the same names are characters in MM 1-5 are rarely the same characters. It's just recirculated names.
One of the excpetions are the pregens in MM3 who reappear as NPCs in MM7.

HMM4 has community mod to rebalance issues from it's abbreviated release.

I don't get why turn based strategy game and MM are being lumped together, very different games

I used upgrade as I wasn't sure which word to use. New engine? New coding? New design? What I was going for was that at games 3, 6 and 9, they had a new engine(?)... that was the upgrade I was referring to. Yeah, that was neat.