For me personally, Overwatch is a historical landmark. I've loved plenty of shooter games, but none of them have ever made me love their multiplayer. The closest was Halo, but it's more because I wanted to love the complete package of Halo, when the singleplayer campaigns have what largely resonated with me.
Overwatch is literally the only multiplayer that I've ever become so obsessed with that I come back to it. I currently have more than a hundred hours into it, and I don't see myself stopping soon. It is literally preventing me from playing other games I might enjoy, Titanfall 2 being one of them. I have it, and want to finish the campaign, but Overwatch is in my PS4, and I always end up thinking "Just one match before I play it" and it never ends up being just one.