Anti-Armor ships are best treated as specialist Fighters in the sense that they work great against Bombers. They do 68% of the damage to Bombers as Fighters, but they've got 2.5 times the range. This means unlike Fighters, they out-range the Bombers. They don't quite match Bomber speed, but on defense with Command Station speed boosts, they can kite Bombers forever.
On the other hand, Anti-Armor ships have bonuses against the big boy toys in the form of Heavy and Ultra-Heavy multipliers. They even have a Structural modifier which isn't very common. This means they actually act a little bit like long-range Bombers. Which brings up another little feature: they don't cost ANY metal to make. This means they are really easy on your economy if you are building metal heavy things...like Bombers. As a result, if you end up losing all your Bombers and Anti-Armor ships on say a suicide raid against Guard Posts, you can replace them at the same time much easier than you might expect. Also, because they have a higher cap than Bombers, against insta-kill weapons like Ion Cannons, Anti-Armor ships are superior because they half the firepower of Bombers to Ion Cannons.
Note that while they are great against anything with a decent chunk of armor, they are paradoxically for a ship called "anti-armor" not at all effective against max armor. This is a weird feature of the armor/armor piercing system. But against any golem except Armored, they'll do wonders. Same for several other large AI ships, including notably Carriers and Spire Siege Towers.