From what we were shown in TW2 both of them are driven by simple and boring motives, maybe they'll find a way to put some depth into their stories and agendas in TW3. That said I'll still go with Iorveth, I just like him better.
Almost done with my witcher 1 playthrough 2nd time that is. I took the path of an elf lover and will do so with my 3rd witcher 2 playthrough. It is pretty hard to like the scoia'tel path in witcher 1. I just want to experience how the order in the witcher 2 will want to burn me alive when I reach chapter III in W2.
My Geralt went with Roche except the end where I saved Triss(ergo most mages) and not Anais. I also saved Iorveth in Vergen so that will be interesting. Looking forward to help Roche and Anais if I meet them again and having Iorveth remember my samaritan choice.
Unfortunately I will maybe run into Dethmold, and probably Henselt as well.