The Hero Hunters Best Heroes are going to be characters that have a higher star count. Sometime though the best possible choice will be the strongest players that you have. In the beginning you wont have much to choose from and upgrading who ever you can find will probably be your only choice unless you decide to spend real money.
The Hero Crate in the shop that cost 300 gold is probably one of the best places to find a good team player. The more stars they have the harder they will be to get from the crate. Getting characters from crates can be risky and is a lot like gambling, but you can find full heroes without having to collect fragments. In the beginning of the game Hero Crate can give you a big advantage when it comes to building a strong team.
The Black Market is unlocked at team level 10 and is a great place to find fragments for heroes. Some though will take longer than others to acquires as they will need more fragments the stronger they are. If you scroll through the long list of playable characters in the heroes tab you will see a star rating that goes all the way up to 10. Unfortunately, right now it seem as though there are no 10 star heroes and they highest they seem to go is up to seven stars which includes the Prophet and Artemis.
If your trying to get the highest rated players it’s going to take some time as the only way seem to be collecting their fragments which can be time consuming. If your lucky you might get them in the crates, but they might not even be in there.
All players will have a starting power rating that should be taken into account before acquiring and upgrading them. Your going to want to upgrade the best you have so that you don’t waste upgrade parts and can have a higher max power rating. Stats can be checked before someone is acquirable and playable so your able to look ahead slightly when it comes to building a stronger team in the future.
If your looking for more related info check out the Hero Hunters Wiki.