While I really like some of the ships already mentioned, allow me to submit my favorite 3 that haven't yet.
F-CFS+ So many people think this thing is a dog. I will pound a R-KHK flatter than hammered dung with it.
F-CFS+ has 8 photons from range, 4 drones, and can charge a rearward, OV photon at 31. Game OVER.
R-K7RB Very strong boat at 170 mid, excellent power and arcs and transporters due to klingon hull. Only challenger is the ISC , and the match is a standoff, where the ISC wins the open space battle, but if the Rom puts his butt in the corner and reinforces, he can force the ISC to come in, and eventually, under those conditions, 2 F torps is worth more than a ppd.
Syndicate BR2 The STRONGEST ship in the game at 130 mid. 2 S torps, 2 drones and 4 phaser one, 127 bpv. Holds its own castling, and always has the option of charging everything up, then doubling engines for the screaming tractor 2, speed 31 rundown, culminating in 2 S torps and a scatterpack.