I tried making this look less confrontational. Please don't take anything the wrong way. I just don't know how to put it less bluntly.
Curetes
Tell me why I should build anything else? They are incredibly cheap, nothing kills them, and you can spit hundreds out in no time. Neither Erebus nor Moros nor Prometheus can match them. You literally build them faster than Erebus, and the shields are so powerful (especially with E), that even Thanatos get owned by them. They are broken in every sense of the word. The only thing they can't do is kill a Heph.
Pallas
As yet there aren't space mines in a E uni, with the exception of HG. In HG Pallas are useless because you can build mines with a Foundry, which you can't do with Pallas.
If you made Pallas a foundry-based ship and brought space mines in they would have a use. But nukes would still be far more effective, and Curetes as well. Pallas are just too slow and vulnerable. They are like a knockoff version of an Ares. A little bit cheaper, but less versatile and slow.
Empusa
Not at all useful against Curetes. Especially since they are incapable of defending and suicide themselves in the first round of an attack. You're better off building Curetes.
Moros
Make them cost the same as Curetes and they will counter Curetes. Otherwise they are just a slightly faster-than-Prometheus Heph killing ship. If I can build 100 Curetes in the time it takes to build 1 Moros, then they don't counter Curetes.
Erebus
The stats are too low though. Conquest doesn't have E, and E is a big deal.
Erebus
Hull Rating 625 +31.25 per E level
Shield Rating 20 + 1
Weapons Rating 20 (60) + 1 (3)
Curetes
Hull Rating 400 +20
Shield Rating 1800 +90
Weapons Rating 100 +5
For each E or aws level, Curetes gets more than ten times as much benefit as Erebus, and Curetes takes less time to build. Anyone who spends a moderate amount of $ per month will literally have massive swarms of Curetes in no time. Noone building Erebus or Moros can ever keep up.
It is certainly true that in equal RSP, Moros will obliterate Curetes in a round or two. But you can never achieve equal RSP except against players already well below you in rank.
Triton
That could work. Not sure it's an easy fix (technically speaking), but if it is I can certainly see it being unbroken by such a stipulation.
