Who is best female singer to Sing with Thalaivar

[pulavar]

HI Experts,

I am just wondering who is best female singer to compliment Isaignani...

I think is Uma Ramanan. Some songs...

Bhagavathipuram Railway Gate - Sevvarali Thottathile
Geethanjali - Thulli Ezhunthadhu
Paattu Paadava - Nil Nil Nil

I am not a musical expert. Lets here from experts.

Did Vani Jeyaram had any songs (duet) with Ilayaraja?