starting from the team & developer background in managing previous projects, then based on what products they offer to the market, whether real use cases or not. yes, that's my first reason before investing in cryptoqurrency. especially about coins with real use cases.
Of course you will check first the background of that altcoin you choose to invest with. Second, it is a big factor to consider the developer background and how appreciably economical the products of that altcoin are. I'll bet that every altcoin has the ability to become productive but then all of that success were depends upon how successful the background of that crypto was.