Grossly there are 4 kinds of altcoins:

1- cryptocurrencies like LTC, XMR or ZEC

2- "platforms" like Eth, KMD or XBY

3- Securities : tokens used to crowdfund a company

As for number 1 there are few that will thrive and be part of a larger market with more than one crypto ( my fav now is monero)
For number two Eth is establish but i fear for the enoumous mount of junk built on it. I´m looking at Komodo and Xby. ( There are others off course!!)
For number 3 there are lots of them and the trouble is that you invest but don´t get a piece of the company and sometimes you are left with a useless token...

The 4th group it´s the trully new or enovative stuff. maybe IOTA IDK

In this sea of stuff there is lot´s of crap and scams the problem is finding the good ones...