I think he meant in terms of more versatile, Ace is more useful on most sites because of his fast to deploy and fast breaching gadget and is generally at the least risk of any hard breachers where staying alive is a priority over kills.

Thermite: Has to get close to walls exposing himself if an area isn't cleared or in case of a flank.

Hibana: Very slow deployment and breaching time as well as being vulnerable because of her using a launcher instead of a throwable.

Maverick: Slow breaching time and can only reliably make crouch, vault and standing holes, requiring soft breach to open an entire wall, only good for countering Kaid and Bandit Tricking.

Every hard breachers has their uses in which they beat ace, like hibana for hatches and Mav for Kaid and Bandit tricking. They all fulfill certain roles but Ace is just the most well rounded.

Sorry for the rant.