Coins like BTC and ETH have proven beyond reasonable doubts that they are the best and more safer coins to invest. My little advice is that, whenever you get your altcoins, it would be better to convert at least one third to either BTC or ETH to serve as some form of insurance to your tokens in case it fails to survive. I used to keep all my altcoins and now that the market is red it has badly affected my investment. And mind you, those new altcoins are not like BTC and ETH, they can get zero volume anytime so they are not reliable. Is there any other person with a different view or everybody agrees with me?
Either way can be a good strategy. It depends on the need you have. If you have a great need of having your own currency to use for something that needs to be prioritised, go ahead and sell them and convert it to ETH or BTC. But if you believe in the creators of this certain crypto, keep it and let it grown in time. Bitcoin was once a nobody cryto but look how it bounced back.