Play Axis then. You seek the wrong unit role or performance.
The Ostwind is the only tank with similar design as the Centaur and I prefer it because the Centaur's 160 armor only helps it against a P4 at best, not against any other Axis AT weaponry. The Ostwind being 20% faster than the Centaur helps it against all AT weaponry.
The P4 was an example, I'd actually take any stock medium tank over the Cromwell. You trade some speed for more AI (both P4's, Sherman and T34/76), more AT and survivability (both P4's) or far lower cost (T34/76).
The Panther is the only stock advanced medium besides the Comet, so they're most closely comparable. Easy 8 is on a shitty doctrine and for the cost of your first Comet a Soviet could get two T-34/85's.
Go to your documents -> my games -> coh2 -> playback, there will be a file called "temp" which is a replay of your latest game. Upload here on coh2.org in the "replays" section.
again with this meme, every ukf tank is good from stock, the centaur rapes infantry and LV, the ff has 200 damage 60 range and moving turret, Cromwell is a better Sherman without AI related ammo and moving accuracy, the comet is a mini tiger but it could use a vet 1 reload buff (and check if the main gun has a projectile), it already has very good pen and armor(both almost tiger lvl with only 10 less armor and 30 less pen at all ranges), 45 range and 800 hp, and obv almost as fast as the Cromwell (to the people who feel that the AI is alcking, it's just that the damage is shifted more to the mid range but has less one shoot potential ex.: the tiger does only 26 damage at mid range AOE while the comet does 64, both cromwell and churchil are similar, sacrificing one shoots for more consistant damage)
Not saying they're bad, but they're decent at best:
Centaur? Give me an Ostwind that's far faster so it can actually get away while having similar AI/AT.
Cromwell? Give me a P4 that can actually damage inf with its pintle, while having better combat stats.
Firefly? Give me a Jackson that has better rof and speed and is effective without being a muni sink.
Comet? Give me a Panther that has better AT and survivability and a pintle that also gives it better AI.
Churchill / Crocodile? Gimme dat.
Centaur can be given a pass because it has its merits, but I would not ever call the Cromwell, FF or Comet the best in their class (price/performance wise).
Also, about Comet vs Tiger AoE: compare AoE distance please.
I didn't watch the replay, but was it a flamer Engineer blob?
If so: try multiple MG42's with an LMG Grenadier blob in the back. Flamers have to get close to do damage, so keep at range. They also don't have snares, so feel free to bully them with light vehicles.
JgPanzer 4 - Range 60 <- Not high pen like Alphrum implies (170 far, same as Stug)
Pak 40 - Range 60 <- Not a tank destroyer fyi.
Elephant - Range 60 (80 in Hulldown) <- 70 range actually, try to get that in 1v1.
JgTiger - ? 60 or more <- 80 range actually, try to get that in 1v1.
Etc, Etc <- Ran out of things to list.
Sorry, had to make this reply out of obligation.
On topic: Churchill is not a problem, it's the only "good" stock tank of UKF. You could make a case for the Crocodile though, we will see after the heavy tech lock + Tommy nerf patch. Against Churchills: just get enough AT guns and Stugs/JP4's to keep it at bay and avoid chasing it (it's a trap!) It doesn't have that strong of a gun so probably won't do too much damage.