I wanted to trade IOTA and registered on bitfinex for that. I guess this exchanger is big, trusted and containing coins which are not listed or bittrex. As for mobilego, I can see it on many markets but I guess Liqui is the most trusted one among them. I think you should go there, for it's too risky to use unknown exchangers. Even famous one have some hacks and robbery from time to time. If you feel that this coin is great as a long-term investment, you should install the wallet and keep the coins on your computer.