I have two favorites: Bitcoin and Ethereum. Bitcoin because its first coin and very perspective, long time stay in first place in the list. Almost everyone in the world hear about it. alot investors trust in btc. its mean that more trust btc has so let more chances to develop. Etherium, because its offer a system for easy conducting transactions, and also the technology of smart contracts that can be used for business.
I think that soon the most popular cryptocurrencies Bitcoin and Ethereum will start moving towards each other. I mean the opposite sides of their development. The fact is that I am gaining popularity, and Bitcoin is losing relevance.