From what I've seen, certain crown companions are just plain under powered compared to companions you gain through questing.

For example; Peter Quint is a companion that buccaneers get early on in the game. He is by far one of the best buccaneer companions because of the fact that he is able to get relentless, vengeance strike, blade storm, and second chance.

However, the Helephant Destroyer you can get from the crown shop is a different story. For $10 you get, in my opinion, an inferior companion compared to many that are available for free. The Helephant Destroyer starts with hold the line and has the ability to learn blade storm, repel border, vengeance strike, and cheap shot. He has the potential to be a fairly good companion, but he pales in comparison to the likes of Peter and even Barnabus. He isn't a buccaneer I know (he is a privateer), but he seems under powered. After he uses his epic strike ability, he becomes kind of useless. He frequently is only able to hit once per turn and for mediocre damage.

I get that not all companions can be super powerful, but some just seem under powered and therefore aren't really ever used or viable. The Helephant Destroyer I suppose could be good for defending witch doctors or musketeers with his hold the line ability. Even then, there are other companions that would be better at guarding ranged companions than the Destroyer.

This is all just my opinion and I realize that KI doesn't want the game to be pay to win and that companions recently received a buff a few months ago, but I just feel like more could have been done for the companions that are under powered.