My favorite coin to buy is Bitcoin. Besides it, I believe in XRP and Stellar which have been growing by the market capitalization even during the downtrend. Also, IOTA can soon get into the top 10 due to dealing with the IoT market.
I really don't understand cryptocurrency to be honest, nothing really backing them, the behind the scenes of some of the companies is murky to say the least (especially bitcoin) which they use to then manipulate the value of the coin. If i were to invest in any (which I have thought about doing a few times) I would literally speculate with a small amount of money on some of the lesser value coins on the off chance that they make a move.
No one really understand the background either but there are still many people taking risks in these coins, some making money while some ending up their life savings to the hand of scammers so better becarefull while investing in such projects.
I miss those days. Even in early 2010s when the price was sub $500. The funny thing is that the only thing that has solidified Bitcoin into the actual market is the darknet through illegal purchases. As soon as crypto is viable across markets, it should settle and become more viable for trading / investing.