Truth be told, I got a lot more enjoyment out of Dragon's Dogma than I did Dark Souls. Kind of hard to compare the two games though, DD's "open" world is lot different than DkS's. DD is more like a Japanese version of western series like Gothic or (ugh) Elder Scrolls. It isn't necessarily as easy as Pyros said either; it's just that you're able to grind levels and abilities to much greater effect than you can in a Souls game. If you head straight to Soulflayer Canyon and the Greatwall area right after starting out, you'll find it very challenging. (I can't actually remember why I felt the need to do that when I restarted my game after having played 10 or so hours, but I know I had a really good reason. Don't think it was just as simple as wanting items from the canyon chests, it was something at Greatwall that I was after...)
I played it before Dark Arisen was even announced too, and it's pretty much universally agreed that DA made the game even better. I still need to play DA since it was free on PS+, but just haven't gotten around to it. :/