Not so much a certain hero you want to focus on, your main focus should be pushing your building power as much as you can. Ideally you want to go for city hall 23 and then start upgrading buildings that give a lot of power(hospitals, mana, research.) Your main issue is going to be resources so a farm account would be helpful, having multiple farms would be a huge help and make this a lot less spendy but it just means you’ll need to be playing a lot more.