Which is a very weak snare.
Given he already is playing a Necro, that would be pretty unnecessary given he plans on boxing the two.
But yes HP regen is a large draw to Troll shaman. Also JBB but post 55-60 it is much less useful.
Ogres have frontal stun immunity which is nice if you intend on tanking on the shaman with Slows / HoTs it can be pretty useful.
Iksars have AC and Regen working for them.
Personally I'd go with Iksar or Ogre were I to make a shaman. Ogre is better during like... Kunark/Velious when slow tanking is very viable in highend content like Sebilis or Kael... IE if you were in a time locked raiding guild @ level 60. However PoP mobs hit pretty dang hard so even with slow you can't tank all that well without lots of AAs/raid gear.