First priority is being able to do all the rare quests. You look already there. I’d on-color level more heroes to level 60 so you can stack well. Like @FraVit93 says Caedmon and WuKong are quite useful. I’d also look at what classes you are weak in and prioritize beefing those up as you go along.
There’s no hurry to get any hero to level 70. For raid tournaments, it’s to your advantage to avoid leveling heroes beyond 60 until you have a compelling reason. That reason could be the ability to progress further in a seasonal event or to complete legendary in a monthly.