What about international school in Budapest?

Hi, everyone.
I am trying to find a international school for my little brother. He is 13 yr, and just move here.
There are several international schools like American International School of Budapest, International Christian School of Budapest, Greater Grace International School and etc.
Any ideas about which one is better, and any comments on those schools?
Someone told me GGIS is a good school, but I am not quite sure...
Need your help, thanks a lotttttttt.....:)