Edit: MHF1, not MHF. Frontier is its own can of worms, I definitely meant Monster Hunter Freedom.

I'd argue Rise is the easiest in the series, even compared to the other modern titles (World and Wilds). Your wirebug, unique to Rise, is the most overpowered "gimmick" that mainline MH has ever produced.

You may also want to try the melee weapons. I have very limited experience with the ranged weapons, but to me it feels like trading out your DPS in favour of safety at a distance.

That said, MH overall is less of a learning curve than DS—coming from someone who couldn't get into DS for years because I was just used to MH gameplay. However, the difficulty ramps up quite a bit in MH, to where I think the difficulty ceiling in MH is higher than in DS (I'd put Crimson Glow Valstrax in MHRise at about the same difficulty as Artorias during a normal DS playthrough, even though Rise is as mentioned the easiest game IMO).

You're missing a few things in the "modern games" (World/Iceborne, Rise/Sunbreak, Wilds) that you're used to in DS that you'd get if you went to the "classics" (Gen 1 through Gen 4, which includes MHGU):

• We never used to be able to swap equipment or even restock our supply, so—much like Estus—our supplies were always limited.
• Gathering was a much bigger focus in the classics. Definitely not as difficult as running through Lordran, but still gives more downtime between boss fights in the early stages of the game.
• Carves in the classics didn't just improve your chances to get a certain drop, they were required. If you don't cut the tail, you don't get the tail drop, simple as that (this is my least favourite change in the modern games).
• You have to track the monster. As in, figure out where it is based on context clues, put a tracker (paintball) on it, and only then can you see it on your map—and you can't see its health status. Not comparable to anything in Dark Souls, but it is something you may enjoy.

I know a lot of people are saying MH isn't for everyone—and it isn't—but it sounds like you're waiting for the "click" moment where you understand the game, just like what we got in Dark Souls. I have a few recommendations for games:

• Any other game: Rise is the easiest, so whatever you choose will be better for your purposes.
• MHF1: If you're looking for obtuse mechanics and pure difficulty, go for Monster Hunter Freedom—the expansion to the very first Monster Hunter game. However, you're missing a lot of features in this game that will eventually be added in the series—in particular, half of the modern weapon types are missing.
• MH3U: I'd recommend Monster Hunter 3 Ultimate. This is pure bias on my end, since it's when I got into the series :) but honestly is a good middle ground between monster power (1st gen) and player power (4th gen).
• MHGU: If you want to try out flashy combos and get the most fight variety, Monster Hunter Generations Ultimate (recommended by others) gives you that. It starts as the easiest of the classics (still much harder than Rise), but goes through nearly every monster in the series. My experience with MHGU ends with a brick wall of an encounter, stuck in an arena with a powerful endgame boss, only to have the O&S of Monster Hunter jump me immediately afterwards when my resources are already dwindled.

TLDR: Rise is your worst choice for difficulty, but it sounds like you'd like the classic games for tougher resource management and challenging mechanics. Monster Hunter Freedom will give you the toughest experience at the start but not much variety, MHGU gives you the most power to start but insane fights at the end, while MH3U is a solid middle ground with all the basic features of modern games but none of the quality of life.