A lot of discussions on forum are all about "what coin should I buy? Why?"
Here's the opposite - I want to ask what alts you would never buy and why so.
My example:
Never buy BTT, Tron, Stellar and other coins where the tokens are giving away with all kinds of airdrops. Why? Emission grows with no influx of investors.
Doubting about Peercoin. Hybrid emission system doesn't seem reliable too, though lately PPC began spreading itself via well-known exchanges (changheangel or changelly - don't remember).
+ Libra. Not sure if any explanation needed.
There are too many alts and most of them are short lived. It is sad to think that those projects ended briefly after all those months of advertising and hype. Searching online, you could see almost the same coins in the top 50 list so my opinion is not to invest to the coins lower than that rank but I can be wrong because those low coins might still have chance to grow when we least expecting it.