Suggestions for my next 4 heros to "master"?

Well basically the title, I usually pick a hero and then play him/her until reaching rank 10 but honestly sometimes I have thrown games because I play with X hero even if I don't get the specific role (somehow manage to win as jungle Kira lol) but I don't want to be a bad teammate doing this anymore (also playing the same hero for so long gets boring eventually) so I'm asking you, which 4 heroes will you say are the more versatile role wise?

For reference the heroes I already have at rank 10 are 1. Murdock 2. Yin 3. Skylar 4. Boris 5. Steel 6. Kira