Ok, so in my honest opinion the Ranger is lame in comparison to the Necromancer in regards to a pets character. By level 31 a Necromancer can summon a 1 Healing Blood Fiend, 2 Bone Minions, 1 Shadow Fiend, 1 Bone Fiend, and 1 Flesh Golem… all of which are persistent. That’s 6 pets that are all out at once, which way more than a ranger’s 2 out at once with a nature’s ally every now and then.
I can run my Necromancer as a total melee character with a dagger/horn combo, or use a staff to mastermind from range. With specializations your pets become more awesome, so there is no comparison in my mind.