AR Rahman is God so far as instrumentation goes.I believe he still can improve in the melody department.His best ten in my opinion are:
1.Chinni Chinni Asai:From the blockbuster Roja it
combines beats with melody.Soothing for any ear.
2.Thilana Thilana:From Muthu,its just heavenly,specially the beats.
3.Chika Pukraile:Pardon me if I have got the words wrong,this song from the tamizh version of Gentleman has great beats with real techno sounds.
4.Awara Bhoiren:Hema Sardesai sings her heart out with great words from Javed Akhtar.
5.Phoolon Mein Jo Khushboo:This Jeans number is lyrical and so befitting Aishwarya.
6.Yeh Haseen Wadiyan:This song from Roja has Chitra making you feel like you are really in the heavens.
7.Chal Kheva Re Kheva:This song from Doli Sajake Rakhna has a unique feel and was well executed on screen.
8.Humma Humma:Sonali Bendre,Remo Fernandes and Rehman.Need one say more.
9.Ghanan Ghanan:Classy,earthy and very unrehmanish.
10.Satrangi Re:From Dil Se.I am of the opinion that none anywhere can make this tune.Has shades of RD Burman in Teesri Manzil or Caravan.