I have bought BitBall, stellar, engine and some Ethereum after doing some research.
Exchange tokens are like thousands out there, exchange closes and down goes the coin and the funds with the exchange.
I am OK with Ethereum and Stellar, but in my opinion it will be better to stay away form these smaller and little known coins such as Bitball and Engine. Most of the smaller altcoins have lost 90% or more of their value during the last few years and there is no chance of a revival lurking in the horizon. The best thing to do will be to trust the established coins.