Tataru with Minfin as a close second.

Tataru ended up on my list when she kept sending me on stupid quests that pretty much amount to a pity party where she then tries to be useful by...what? Not doing the one job she has as secretary and forcing the WoL to stop what he/she is doing to go find her or pick up her freakin mining tools from halfway across Eorzea? Yeah. She can go. As for Minfin, she is useless but at least she generally stays out of your way and doesn't make me go get tea leaves in Dragonhead. When she isn't getting captured or calling you on the link shell to tell you to come ALL THE WAY TO VESPER BAY so she can have a five second conversation, that is. So ideally, an explosion would take them both out and I could have a party with the Scions that actually matter.