Soldiers have 2 things:
double hp which is OP for tanking and dueling and tactics which isnt really meta due to resistance but its useful for dueling too
Duelers have 2 things: crits which is OP for damage and dueling from afar which doesnt make you stronger but it allows for "surprise attack"
Workers have 1 thing: the aim/dodge bonus, 40% bonus doesnt allow for them to be serious contenders for top damager or top tank (dodges + hits taken) of the battle but whereas the dueler and the soldier are very RNG dependent, they can do a great battle and next battle horrible stats, workers arent so RNG dependent, they have consistent stats, and their average is only slightly lower than a soldier/dueler from the same level.
Now the hard part. Adventurers. Adventurers have 1 thing: Ghosting. But that is so situational! A soldier will have double the hp in EVERY battle. No matter what. In a battle 10 vs 10 (those happen in some worlds) an adventurer will have
0 utility. He gets shot by the 5 damagers and ghosts the 5 tanks. If its just to ghost 5 tanks you better have a soldier tank blocking. For ghosting to be useful it needs to be in a battle against a lot of enemies, your side needs to be in a position where it needs to block a sector with a lot of LOS on it (usually towers, flag or North sectors). And even in a 132 vs 138 (colo caps) you want like ~10 adventurers (unless you are planning to use the turtle strategy), not 25% (34) adventurers. As said by an adventurer here:
i play HP adventurer and since there arent much players and battles arent full and blocking sectors isnt a thing anymore, adventurers bonus is actually more like disadvantage than bonus - i cant event tank well, cos people wont shoot at me..

i have to buy premium without VIP - without character-bonus, so the chance that people will shoot at me is at least 75% and not 50 %
Ghosting plays against them at some point. Like they take first few shots and then they ghost, problem is first few shots are from the best damagers, they cant even farm the easy dodges or low dmg hits of other tanks cause they are already a ghost by then. Another thing that can be used is to "pile" a lot of adventurers on point with the idea that when 1st adventurer ghosts the adventurer behind keeps tanking but with soldier/worker not only you have better individual stats you dont have to resort to such "crazy tactics".
All of the other class bonuses are nearly irrelevant due to modern sets.
If I had an infinite amount of players from each class signed up to a battle and had to make a team of 138 I would take 60 soldiers 60 duelers 9 workers 9 adventurers (and this is me doing max effort to take the 4 classes, some IFBC battles didnt have the 4 classes)
Considering all of this the class that suffers the most is adventurer.