Pets are usually a skillpoint sink -- you'll want to dump at least 7 points on Wolves so you can summon 2 of them. If you'd like 3 of them, you should dump 18 points in which case you'll need equipment that provides "+skill". So if you want to expertise in Hunting mastery, you don't really have the choice to have both wolves and nymph, at least while playing on Normal.

Wolves are good for distraction and tanking at lower levels but at some point, near or after the midgame on normal difficulty, they'll die too fast to be useful enough (Heart of the Oak helps boost the total HP hence improving their survivability especially when you have Survival Instict). Later on in Epic & Legendary they prove useful once again since they get strong enough due to the health bonuses they receive. Strength of the Pack is a great skill to have since it comes with some useful buffs on speed and damage. Maul provides the ability to do bleeding damage which is nice since it leads to a slow death while Survival Instict helps fight more aggressively when health drops below 30% while at the same time damage absorption is increased.

As you see, if you want your wolves pack to be strong enough, you'll need to allocate quite a few points in them and their skills. If you choose the pet road, don't forget to add some points (even better if you can max it) in the very useful Heart of the Oak which bolsters the speed & health of you and nearby pets.

Nymph will die a lot (actually she is the weakest "pet") and although she has some nice damage potential, I wouldn't recommend her over the wolves, especially in higher difficulty where the wolves are very good.

All in all, Nature mastery compliments Hunting mastery very well and I think it leads to a very nice gameplay experience (although the same can be said for several other combinations as well).