You actually do not have much of an option as to which exchange you want to withdraw your crypto after ICO. Everything is in the hands of the project developers. The most that you can do with it is to suggest to them your choice of exchange. Apart from that, you just have to wait for their decision. Well, there are a handful of decentralized exchanges and you have the option to go there to sell your coins. However, it would be better to wait for the major ones really.