Well this is going to be a mixture of Tam and hindi songs..

But all the people who don’t know tamil don’t worry, love for music transcends all languages.

My favs are

a) Azhage sugama [Parthale Paravasam]

A beautiful song set in the raag Sahana makes you feel the sorrow of ’Vibralambha sringar’ [for the hindi folks] or the sorrow of seperation from the beloved. My favorite.
This song is best enjoyed alone... looking out from the balcony....It touches ur heart somewhere.

b) E- ajnabi [Dil Se]:
Do i need to say more about this soulful song?

c) Dhim tanana [Rythm]
This song is a masterpiece both in tunes and in lyrics, in which a water is personified into a woman

d) China chinnai asai or dil hai chotasa [Roja]
The song that catapulted Rehman to stardom

e) Hai rama / Pyar yeh [Rangeela]
No words to describe these lovely songs. His first only hindi film

f) Alaipayudhe- Pachai nirame / [Sathiya... in hindi]
A long song. But you never feel the song sagging at any point.

g) Bar Bar ha... [Lagaan]

h) Yeh jo des hai tere [Swades]

I get goose pimples when i listen to these songs... Rehman’s voice is out of the world.

i) Muthal murai killi parthen [Sangamam]
The lyrics won the national award... The music too should have won. But i guess rehman was winning too much for them :)

I really wanted to put many songs but one won hands down for the last position

j) Vellai pookal - [Kannatil mutham ittal]

Mani and rehman’s combi- Need I say more. I cant help getting tears in my eyes. This was composed for the scenario of the Lankan war - Let peace dawn.

It was difficult. But I made a choice. If anything is missing then please feel free to put it in the comments.