Which hero to add to pool?

I made it one of my goals this year to get to Legend (I'm currently hovering around 2k) and so I picked 4 heroes whom I have fun playing: Zeus, Sniper, Viper, and Alchemist to learn to play well. But idk if this is a big enough hero pool, as the first two are both glass canons. So are there other heroes I should learn to flesh out my hero pool? Thanks:)