Yeye I understand I was talking to Kate... who is giving you information based on his/her experiences but he/she is vip15 and rank 1 on 1st to 100 on that server, so that information is completely screwed.
Once more people turn 100 and another 3 months has passed that team is not working as he/she will run into those heroes I mentioned.
On lower levels cof is most likely zem kong taurus jasmine lumos nilya xanos valan and if u managed to get a free vulko, then vulko and if you were lucky with gremor or alecia as box hero then those aswell.
Heroes that do well with a full energy bar are ember (yes ember), flora, lingling and you should fill their bars and then only use them when you're in a pinch.
On my free to play account my team now is Valan Taurus Gremor Alecia Nilya and it can run from start to finish (at level 63 and my heroes are just p1 no gear at all)
Alecia's ultimate just kills entire teams on her own, so trying to grab her in 1-4 10 pulls is a decent investment, although in the long run she won't be that great of investement.