The Salthi are pretty bad, but I love their Sartha descendants. They're not well armored, but a squadron of those little punks can wreak havoc as I so painfully discovered recently in Standoff.
As for Terrans, I don't know. I never really cared for the Scimitar in WC1 (though ironically it was my favorite ship on the Wing Commander MUSH a few years ago but I don't think the specs were right on with the game). The Hornet is an excellent light fighter and reconaissance ship and I used it splendidly in SM2, but I can see why some of you who stayed and dogfighted Kilrathi fleets would hate it. I suppose I must concede with the general consensus about the Epee and the Hellcat... they just didn't handle right. Aesthetically the Hellcat was nice but it just didn't work for me.
My favorite is the Rapier Mk II from WC2 and Standoff. It's just the perfect dogfighter. It's fast, maneuverable, excellent shields, and a great loadout of weaponry.