These days new Cryptocurrencies filtering is pretty easy I would say. The best way is to move where major VCs are moving, we are currently in the VC backed era of Cryptocurrencies where only the currencies which get such funding in early stages are able to succeed rest of the currencies are not able to make their mark. So you just follow the major VC funds or follow around Crypto news websites to see whether some currency got any backing from a VC. This can be a good filtering criteria.