British English is the original English from which all other accents stemmed (American, Canadian etc) and so is the best to learn in my opinion :P

i think American english is easier than british so i prefer american

Absolutely British - Shakespeare's English, if possible! :) Even if I'm Italian, I can easily understand songs and films in British English, while American English is quite another language to me - I understand nearly nothing of works in A. E., and literature is a problem too: all those abreviations and different terms (lift vs elevator) and different verb constructions (lie and lay...). But the worst problem is accent - like if you always chew a gum while speaking: difficult to imitate and to understand!

although i learnd british in school,but i prefer US accent cause i think it's easier to deal with

It depends. There are both accents from the US and UK both that are grating on the ears. I personally prefer a sort of neutral, sort of Northeast educated American accent.