SF FO Tie is spot on, probably the Command Shuttle too (some use during the TW bonuses a while back). The Sith ships are subject to debate, the combined Sith-Empire fleet is not bad, but not meta breaking either.
Clone ships (Fives especially) are/were part of the Mace time-out fleet and JC was common in the early days of ship arena (and probably synergises well with the upcoming Negotiator).
Gauntlet is a less frequently used, but even that ship had its days.
I agree that the Rebel fleet has had a way too log reign, but it's not like you can grab a set of old ships and make a brand new meta without adding anything new. Negotiator will likely 'revive' the GR ships and it'll be the Malevolence that probably brings a few new ships.