I found Navi to be most annoying because unlike the others her pointless text sometimes you cant skip. I also found Midna to be least annoying, because her advice typically wasnt useless, and most of the time she just shared humorous opinons rather than pointless advice.
I really like all the helpers. Obviously Navi is the most annoying, but she tries to help
Midna is my favorite because of her story.
Tatl is awesome because she is so sarcastic.
The least annoying though would have to be Fi, unless you count the stone that tetra and the kind comunicate with you through from windwaker. It barely ever spoke.