It's hard to prove outright, but the crypto market is essentially consolidating toward the 'stronger' and more well-known coins. You don't need to do complicated math equations, just do a side-by-side comparison of the top 10 (maybe top 20-30). (((note: recent ICOs do not apply; too recent, etc).
As the number of crypto exchanges increases, and the number of financial institutions join the market, the 'BIG' money is not going to invest heavily on 2nd rate coins. I'm essentially stating the obvious, but there's more to it. You NEED to start evaluating your own coins and start 'Culling the herd'. Get rid of the lame ones,...the slow ones,....the lame ducks.
Here's how to do it:
a) go to all of your exchanges and write down all the coins you have,.... List them.
b) cross out with a pen those you are definitely keeping, or put a star next to it,.... any way you choose
c) go over the other coins, one by one asking:
1) has this coin moved at all recently?
2) Is this coin original? What are its competitors?
2a) how does it compare in price action recently to its competitors?
2b) which coin has had more progress -- white paper/announcements
3) Does the coin follow the overall market trend? (i.e. go up/down in tandem)
4) Do I own too much? Could my $$$ be better used in a more secure coin?
5) Do I own too little? ..... meaning--is the amount you own so insignificant that it's more fun to just keep it? Was it free? Airdrop?
Why make a list? Well, some of you have forgotten what you own. So, have fun....make a list, ...and then you can slowly ponder which coins you want to keep. Don't wait too long though. My prediction is that slowly but surely coins will start falling by the wayside. Hell,....look what just happened with Bitcoin Gold. 51% attack. I am predicting that this coin, and many others such as Veritaseum won't survive. History will repeat itself--- this happened with the Dot-com bubble back in the early 90s.
One last thought---- If you can't decide,...if you are torn between keeping or selling because you've owned the coin for so long and have become attached to it...... sell a portion of it. Then later you can say to yourself "well at least I was smart enough to get rid of some of it"" Its the same reasoning I used when suggesting to buy in increments (like last month when BTC/the market was down). I bought small amounts of BTC, and now I can say to myself " well, at least I bought some when it was down!!"
Good luck. Don't be stupid/don't be greedy. Just slowly invest and don't spend every waking minute checking the market.