Looking at the vast amount of altcoins/tokens out there it's almost impossible to give each one time to properly research. That's why I have a fairly simple method to verify whether a coin is worth the time to research... before I understand how it works or how it will achieve its goal, I try to understand a simple question:
What problem does it solve?
Bitcoin
Problem it is aiming to solve: The world economy is too connected, and long term is unstable.
Bitcoin is a long-term investment vehicle separate from fiat based instruments; it's a disconnected USD hedge.
Ethereum
Problem it is aiming to solve: Shortest term: the need for a platform to issue ICO tokens (and sell them with smart contracts); mid term: legal contracts are inefficient; long term: AI overlords
Ripple
Problem it is aiming to solve: The banking system is disjointed and contains thousands of ledger systems spread across the world, it'd be better if they all were on the same ledger system; Market makers park insane amounts of capital to facilitate payments where on a more efficient system they wouldn't have to.
Connecting all payment systems on one ledger, providing a blockchain system for banks to use.
Litecoin
Problem: Originally ASIC miners pushing out GPU miners from Bitcoin, recently, all the drama in Bitcoin is making people look for a backup Bitcoin.
Ethereum Classic
Problem: Ethereum shouldn't modify the network to refund losses to those who create faulty code. Code is law.