From most viable to least.
S: Maggie - She has a constantly tracking dog who discourages sneaking. Her harpoon traps are the greatest deterrent in game. Her smg also does decent damage as well.
A: Jack - His scanner has an obscenely large range and does a good chunk of damage when it hits. His repulsor is the best at eating up the monster’s traversals and rescuing team mates.
B: Crow - Crow has Gobi who can scan one area while you search the other. His kinetic rifle can pierce through the monster’s armor (albeit chip damage). A well aimed stasis shot can enable Crow to switch to his rifle or Gobi to ping the monster.
C: Griffin - Griffin is a situational trapper. He can completely monitor the entire area on small maps. On larger maps, he must rely on certain check points to get a clue of where the monster is or going to be. His harpoon gun can be useful for limiting a monster’s traversal or escape but doesn’t serve any other purpose if the monster is aggressive.
D: Abe - Abe relies entirely on seeing the monster to track it. His grenades are useful when thrown from a high area but doesn’t truly slow down the monster. His shotgun is too inconsistent at times, even when slow firing.