想上国外研究生的话，考什么英语好呢

which country are u going to?
if u wanna go to the U.S.A, u should try TOEFL.
if u wanna go to british, Australia,etc, TOEFL will not be accepted when u wanna get a visa. So try IELTS.
I have taken both toefl and ielts. personally, i think the latter is easier.
GRE and GMAT are only needed if u wanna go to a graduate school in the states. However, some great graduate schools in other countries, say, the university of melbourne, also requires the applicators to provide their GRE OR GMAT scores.

So , first and foremost, u should know which country u wanna go to.
Good luck

GRE,都不简单

去美国的话考托福，并且还要根据你要读的研究生专业选择gmat,gre,或者sat
去英国只需要雅思
相对来说雅思简单些，因为托福对综合能力要求很高，听说读写结合的很紧。

新托福是机考，有一定的难度
雅思是英联邦国家通用的，如果你想去那些英联邦国家，最好是考雅思
也不能说哪个比较简单
都有难度
个人觉得雅思的范围比较广
身边也有很多同学和朋友考的是雅思