So in the end the original DMC is the hardest.....

[Drunkenstein]

No I get it the 3rd game could be considered hardest but in the end the original cannot be topped for difficulty especially on DMD setting.
This is because once you start DMD on DMC you are locked into it, while in the other games you can rely on cheesy tactics far more than in the original.
I mean take the vitality stars as an example, if you run out you can just retreat to a different level on a lower difficulty to farm some red orbs and then get back in business once your inventory is full again. So it's not really a matter of if but when. However, in DMC you can't really do that, yes you can grind "Untouchables" by doing multiple playthroughs but if you run out while doing DMD then you run out for good, as even if you have the orbs you can only buy 1 per mission.

With that said I made it my goal to finish DMD in DMC3 without being too cheesy. What I mean is while I did use Vitality Stars I decided not to do any orb farming on lower difficulty settings. So I just kept going with the flow. First I finished the game on Easy, then Normal during which I collected all Blue Orb fragments I missed. While at it I decided to master all styles in order, and in fact I only finished mastering the last style while already playing Very Hard difficulty. And I only started buying large Vitality Stars after I bought every other upgrade available. However, I usually only used 1 during a boss encounter except for the last fight with Vergil where I used 4. So then I played DMD using the Super Dante costume as I checked and it turned out you only take like 1/3 of the damage in Devil Triger than normal so obviously the lack of health regeneration was no real issue. So while playing DMD I still limited my Vitality star use, I even managed to do mission 18 without using any of them despite the fact it's the one with the chess game and you have to fight at least 3 bosses to complete it. So by the time I reached mission 19 I had over 20 stars so it was obvious I can win, although Vergil made me use nearly all of them, but I was sloppy while fighting him.

So it wasn't as hard as my first time doing DMD in DMC, as back then I didn't know all locations of Untouchables yet, so it was a lot harder than DMC3 DMD. Even more so as I knew I can always retreat to mission 20 on easy to grind orbs if I couldn't do it.

[Director Bison]

DMC1's DMD can be more punishing, for the reasons you listed, as well as it Removing DT healing entirely, But I also think it's more fair. Missions aren't too long in DMC1 so dying without any Yellow orbs isn't that big a deal regardless of difficulty, and dealing with regular enemies shouldn't be a big deal by the time you get to DMD, so it only really leaves the boss fights as the main challenge, and non of the bosses health bars are unreasonable, so the game is simple removing your crutch of DT healing, and asking you to actually learn how to avoid the bosses attacks, and learn when they leave themselves open for attack.

DMC3 I think things are kind of the opposite, in DMC1 DMD enemies getting DT is rare, in DMC3 it happens all the time, and I end up viewing the regular enemies as a bigger obstacle then the actual bosses, DMC3SE is just generous enough to give you a Super Costume after beating Very Hard to make DMD more manageable, where in the original PS2 release you had to beat DMD without a Super Costume. When playing DMC3 DMD without a super costume it feels a bit off in terms of how much health the enemies get cranked up to. DMC1 DMD feels like the intended difficulty to play the game at. DMC3 DMD doesn't feel like it's the intended difficulty to me.

[Electric Cupcake]

3 is nowhere near as hard as 1.

Mainly because 3 lets you replay each stage to practice and perfect it and farm orbs to unlock upgrades.

DMC1 makes you play through the whole thing in order, and then railroads you into the next harder difficulty instead of a NG+ on the same difficulty.

[SilentBlack]

if u go for A rank or S rank dmc 3 is harder than dmc1 (not by a lot tho) , for a normal playthrough in dmd using items dmc1 is far harder than dmc3 cause the things u said about items. in the end both games are the best in the franchise lol

[Darth Vader]

For me, DMC1 is the most difficult, the mobility and skills are much worse than DMC3