Armor is really important when fighting low attack units.
A arb has 6+4 attack. Take away the 2+4 armor a generic cav have, and you’ll see that they deal 4 damage a hit (thats 37 hits to kill). A pala has 3+4 armor, so 3 damage for 60 hits to kill. A sicilian cav has even more armor, going up to 2+6, meaning its only 2 damage per shot, bringing them to an amazing 70 hits to kill by arb.
However, if they fight melee units, the story is rather different. A champion does 13+4 damage, thats 12 damage a hit on a generic cav/paladin, bringing them to 12 hits to kill a cav and 15 hits to kill a paladin. For a sicilian cav, its 11 damage, thats still 13 hits to kill. It gets a bit better if we look at stuff like lcav missing BF (so 7+2 damage), where normal cav take 4 damage, sic cav takes just 3.
So vs ranged units, sic cav are absolutly amazing to the point of arbs beeing pointless against them. Vs melee units with bonus damage (halbs, heavy camel) they are more resilient, but still get countered. Vs any other melee unit, they are just slightly better than generic and hauberk is probably not worth it.
They don’t really compare favorably to paladins except
This mostly just matters vs. Arbs or units with even lower attack (Plumed Archers). Against Cav Archers and most archer UUs, the Sicilian advantage is nullified or surpassed relative to generic paladins. They can only tank 2 more HCA shots than paladin, but paladins kill HCA faster and perform better vs. enemy frontline units (halb, hussar). I used to play (pre-nerf) Sicilians a lot in TGs, and they’re still good vs archers, but for general purposes I’d rather have generic Paladins once you can afford them.
They are favored mostly by a fact of cost since paladin upgrade is expensive and long and not really a 1vs 1 thing unless lowish elo or niche situations or specific civs.
It’s like a “light paladin” vibe but with cheaper cost
Sadly sicilians are still a bad civ despite this having been hit with multiple nerfs on their cavalier while not getting anithing in return and are not bottom tier, and the cavalier is somewhat carrying still
Honestly, Sicilian cav is lame especially now that the cost is up and the bonus damage is lowered. He only has a small advantage vs arbs, but not really. And that’s because he has 2 less damage than paladins, meaning that you need 4 hits to kill an arb.