We had very good experiences with Selvala, Explorer Returned. Seems unassuming but plays out quite nice. Card draw and ramp on one card, stays on the table because everybody likes drawing cards. Captain Sisay is probably very good, too, especially now that she can tutor up any plainswalker. Price is shooting up though.
We took out the Wurms because getting the excact mana was sometimes difficult and the effect rather plain. I like the Hierarch as protection from most wraths because for us, that is often a weakness of GW. As far a generic beater + lifegain, Dragonlord Dromoka is pretty solid for that spot.