Practially all the runes are straight up improvements to the base skill (if you are talking about using base skill vs adding a rune). The decisions are most about which skills you have on your left and right button, and that usually comes down to something like a spell that does high damage to 1 target or less damage to multiple targets, like you said, and slowing enemies or damaging them.
I tried using Elective mode since you are supposed to set up any spells you want, but I couldn't add the spells I wanted, so I don't know if that was because I was doing it wrong or if I was not allowed to use those 2 spells at once as the Witch Doctor.
I just started playing a Barb and I think it's my fav so far out of DH, WD and Barb, although almost all the skills for her so far are "hit everything around you" with either bleeding or stun. I don't really like the WD TBH - the zombie dogs look stupid and I can't stand his stupid "throw a pot of spiders" move (you can either do that or shoot blow darts). His blow dart move just makes him an inferior version of the DH since you are relying on a ranged attack for most of your damage. The DH is pretty fun, but it kind of feels like Tomb Raider, that version on Xbox Live which is like an arcade shooter. You can just blast everything with machin gun arrows.
