Look for coins that have a way to give returns to its investors. Look for one that has a working product or that can go on operation sooner.
The project should be feasible and practical at current context. Moon mining or creating Wakanda in Africa would only be donations.
In this kind of situation it is hard to find a good one because most of ICO now are scams.
The best altcoin? There's a lot of altcoin that had a great potential and it have a good performance in the market, like ethereum, litecoin, neo etc. But if you are trying to invest it's better to split your money in different coins.