I'd vote for the Tauvri personally. It looks cool, and it's always packing Piranhas and it knows how to use them. Though, occasionally the Seraphim can be annoying, just because if you're fighting a wing of them, for whatever reason, their turrets pick you apart and at least one of them's got the full 11 gun salute poking you from behind.
Most hated fighter? Hmmn . . . . I'd say the Manticore. The Dragon is too rare to really make me hate it, in FS1 it can be annoying, but I'd rather fight a Dragon in FS1 than a HoL Thoth with Prometheus cannons. And while the Mara is cool, it's Hornets are fairly easy to avoid.
So, Tauvri & Manticore for me.