What crypto do you know the most about?
Your question would be better formulated as:
What crypto should I know most about?
Bitcoin all the way. Certainly the most important and cryptocurrency out there. Not only for being the first (which all other copied its tech) but for still being the most decentralized and tested yet.
How to get to know more about it??
Start with mastering bitcoin, probably the best book about bitcoin ever written by Andreas Antonopoulos
https://www.oreilly.com/library/view/mastering-bitcoin/9781491902639/