I got 3 options for LLM in Taxation and another 2 for General LLM.
Taxation
1.NU
2.GT
3.UM
General
1.UPenn + Wharton
2.Berkeley

Where I should go?
Any suggestion?
Personally, I prefer UM cos it's very small program (no more than 10). I, however, worry about reputation in Asia.
I interested in Tax, Finance and Corporate.
I'm taking Int. Financial Law at KCL.

Thank you in advance for any advice.

Congratulations on getting accepted by all these programs! I do not know much about the general LLM programs, but both Penn and Berkeley are TOP law schools. I am familiar with most LL.M. Taxation programs, but I am not sure exactly which schools you mean by NU, GT, and UM. Do you mean Northwestern, Georgetown, and Michigan? If so, then Georgetown --by far-- has the best LL.M. Taxation program out of the three. Georgetown also is in a fantastic location with a lot of networking opportunities. Congratulations again!!!

Than you so much for your comment,
Personally I'm thinking about Michigan because it's very small class size (up to 10). I also asked the student who studied tax both Michigan and Georgetown and he said for him Michigan's standard is higher. Of course, the main reason for me is Avi-Yonah, He's one of the great tax prof. in the world.
What do you think?

Michigan IS a Top Ten law school (and ranked far higher than Georgetown as a law school!) but it is not as well-known for its ll.m. taxation program.

The top three ll.m. taxation programs are New York University, Georgetown, and University of Florida. If it were me, I would go to the best ll.m. taxation program that I can get into, but the reason would be so I could have more job opportunities here in the U.S.

The student you spoke with -- is he from Asia? If so, then he would have a much better idea of which tax program carries the most prestige throughout Asia.

By the way, I would rank prestige over class size. But the fact that you really admire Avi-Yonah indicates that perhaps you should not pass up the chance to study under him? You do not want to have any regrets!