The fact that hitbox size is the most important factor when it comes to choosing a legend is a huge flaw in the game's balancing.The character's abilities should determine which legends are the best and worst, not their hitbox size.
When a Wraith and a Gibraltar of an equal skill level fight each other, the Wraith will probably win >80% of times, even at longer ranges where Gibraltar profits from his ADS shield.
Gibraltar's and Caustic's Fortified ability can't even remotely make up for their huge hitbox. Those two characters (and Pathfinder after he gets fixed) will always be restrained by their incredible hitbox size, despite their otherwise good abilities.
The devs talked about "