I dont imagine that either is better, the way that Blizzard makes this game is to be as fair as possible, as stated above.. the war  stomp would be nice while tanking and the 5% health would also be nice, but at lvl 70 with the right gear, Nelf's can tank and have more of a chance to dodge and with the right gear we become un-crittable so the HP bonus really doesnt matter. I'd say being able to dodge and not take any damage is better than having a whopping 5% increase... that translates to if you have 20,000 HP... you get an extra 1000 because of your racial bonus... when ur tanking a 70+ boss... 1000 extra HP is well... one extra hit you can stay alive, BFD. 

"Warstomp may be good while tanking"???? yeh if u want to fucking DIE, you can only use it in humanoid forms without shifting out of form. Unless you are trying that moonkin tanking spec (which i would advise against) warstomp will just get you freakin killed ina tanking scenario....bear already has a stun anyway....stop being dumb