Hi,
me too, when I play Risen the very first time, I give up too fast !
Now I'm at level 15 and still on chapter I !
I like DKS very much and I just take a look at TW II (so I can't say much about this game now) and I think I go enjoy them all :
DKS in first place, then Risen I think and third TW II.
Personal I don't like turn based combat. Except if I'm playing "chess"

In general I love the genre "RPG" most of all (beside adventure games and puzzle games and aducative games too) and I also love it RPG's are
different to play because of the variation of (in first place!)
gameplay!!
For example : I like the combatskills in Risen (with learningpoints to spend by NPC's) and I like the free to use skilltree in DKS. Two totally different styles, but I like them both, because I love to have
variation from time to time.
Mostly I play 1 or 2 RPG's on the same timeperiod, but 1 RPG I give priority and that RPG I play a loooong time (months or maybe a one year playthrough (who knows?) !