Season 13 will be archived today, starting the next ranked season 14, which in turn runs until June 4!

If you are new to playing competitively, I highly recommend entering the ranked queue during a sale, when other new players are joining in. Outside of that, the regularly hosted NPC tournaments are the best entry point.
Speaking of which, aTastyT0ast has made a new community leaderboard specifically for tournaments:

https://llblaze.pro/

Any player with at least 2 tournaments in the data set will show up in this list, allowing you to look up full ranking history, biggest upsets, win chances, compare players directly and more.