Kelsey raised some good points in the Discord about the Ranger being more durable due to DEX AC potion and healing potion so here are some numbers for that and how they affect how you should see damage numbers:
Let’s run some math on the incoming Chimera damage in the same scenario:
36 (4x9) rend damage average and 14 (3.5 x 4) fire damage.
Ranger with AC 17 (chain + DEX) / DEX +4, CON+2, INT+1:
47 hp (4.5x10 + 2)
18 rend damage average with 50% chance to be hit
7 fire damage average with 50% chance to make 15 DEX check
25 damage per turn, goes down in 1.88 rounds (without potion)
Fighter with AC15 (plate), STR 18, DEX 10, 14 CON
47 hp, same as Ranger
23.4 hp from taking 65% of Rend
10.5 from failing 75% of DEX15 checks
33.9 incoming damage going down in 1.39 rounds
Healing potion is 26 hp with 35% chance to have it with INT + 1 giving 9.1 extra effective hp to Ranger for 56.1 now going down in 2.24 rounds.
Ranger survives 1.6 times as long as Fighter and can deal 68% of damage when prepared with potion of healing and Foe bane. 1.09 net output of Fighter when prepared in terms of damage before down, assuming melee on both
TLDR; If prepared the Ranger can outtank and eventually outdamage Fighter.
However: Fighter could also roll +1 to AC and force a Morale check sooner with its high damage output