Frontal stun immunity, and 75% (warrior) stun immunity on bard Manaless spells and move while casting on wizard
I would just settle for a decent, castable snare on shaman; something better than the necklace. That would improve my EQ QOL significantly without crushing the game.
Rogue main here. First spell I think of is Gate. Maybe Monk/Bard Runspeed AAs (if that's a thing here. I'm new-ish to TAKP).
I'd take the shroud of stealth AA on a cleric or divine rez on a rogue. It's the same functionality as far as I'm concerned.
Bind Affinity for any class that can't do it. It sucks when you die, and your bind point is far away. The chances of losing a corpse become greater, the longer you have to travel to recover it without your gear.