Dragons Dogma is a much larger, longer game, but has overall lesser combat as its more of an action RPG- but a good one, I don't mean to put down DD.
MGR is a short blast of awesome. Very replayable, fast-paced and fun. So there's a definite contrast there- a large, somewhat slower-paced game or a short, intense action game.
Haven't played DmC, the demo didn't do anything for me.
As for MGR's difficulty, it's a control / combat system learning curve for the most part. Once you get the hang of parrying, Raiden's moveset, target / camera management, etc. it's really not a very hard game compared to a lot of hack n slash titles, it just throw you off at first because it's pretty different.
"The act of treachery is an art, but the traitor himself is a piece of ****." - Mike Tyson
I'd suggest MGR out of those three as it was my favourite.
Dragons Dogma was awesome but even with it being a longer game you do feel like there isn't enough content there. The combat is simpler than the other two but the character building is really fun and it lets you try out a bunch of different play styles.
DmC was really fun and the combat was great but if you are a fan of the older series you might think it feels a bit too simple in comparison. This game is more about style than challenge.
MGR- A great over the top action game, extremely fun combat but it has some flaws. This one is more about challenge than style.
I'd really recommend all three, but if it's just a case of one I'd say MGR has the most addictive gameplay.
MGR isn't padded out with extraneous fluff, it's 100% action from start to finish. it's definitely the best purchase.
Pretty much this. Also I think it sounds like you played demo. If you even somewhat liked it you"ll love full game. If your"re worried about difficulty start out on normal. If you get into it like I did you"ll push yourself to get better and beat all difficulties. Most of the time I just beat a game on normal and thats it but this one was different.