I hope you don't mind my reviving this old thread.
However, here are my list among current commentators:
Best 5:
1. Ravi Shastri: quite sensible and to the point. Tells it as it is.
2. Nasser Hussein: Currently on DD National for the Ind-Eng series and is surprisingly good. Sauve, soft-spoken and makes a lot of sense.
3. Robin Jackman: Always light-hearted and is a pleasure to listen to. I wish he would do more commentary...
4. Dean Jones: Brings in some much needed humour. His commentary was one of the highs of the India-Pak series.
5. Waqar Younis: Surprisingly he is in my top 5? Why? His diction may be a bit poor, but he speaks much better than Rameez Raja and his knowledge of the game is also better than Raja. His reaction when Pakistan were about to lose the match to India in the final ODI at Karachi was just amusing! Takes Pakistani defeat much better than Rameez.
I know I have left out some big names, but many of the top commentators of yesteryears are now inactive or I just don't get an opportunity to listen to them in the last few years.
Worst commentators in no particular order:
1. Most commentators on Channel 9 (AUS). Very biased, extremely one-dimensional and boring. Except one or two I detest the lot.
2. All the Doordarshan "specials": Charu Sharma, Krish Srikkanth and company. Nuff said.
3. All New Zealand commentators. Biased, one-dimensional and even worse than Channel 9 commentary team. One word: BORING.
4. Navjot Sidhu. Amusing initially, but began grating on our nerves long before he thankfully disappeared from the scene.
5. Sunil Gavaskar. His "bi.casssu the battu is just-a not coming down straaight. He needs to bring his left elbow strai-ghtu".
6. Sanjay Manjrekar: Improving these days, but still needs work.
7. Ranjit Fernando and most Sri Lankan commentators. Biased, very biased and very nasal.
8. Harsha Bhogle: Thinks he's a pretty smart dude and hence tends to act oversmart sometimes. Irritating at the best of times with his exaggerated phrases and his pretence at being neutral.
9. Ian Botham: Sometimes very biased and makes pretty critical remarks. Otherwise OK.
10. Rameez Raja: I added him here because he's not improved one bit since the time he came on the scene. One-dimensional and Pakistan centric. Very tiring in combination with Sanjay and co. on Ten Sports although any day better than some of the others I mentioned.
11. Other miscellaneous non-regulars who appear and disappear from the scene at rapid intervals...