I'm looking at playing a multiplayer game again for a while and aiming to climb the ladders and actually improve my skills. Out of these options which should I pick up?

I have experience playing all of these games but never really climbed far because I was busy trying to finish every game in my Steam library. Now that I've finished every game I'd like to focus on a Multiplayer game and improve. BUT, I'm having a hard time picking a game to focus on:

Hearthstone

Overwatch