Well my worst ships would be...
WC1 - Hornet, I liked it though, I didn't really dislike any of the ships in the first game, I haven't got to play the SO yet because it isn't working, but I'm sure I'll hate the Dralthi.
WC2 - Epee, you know why, I hated it, doesn't everyone?
WC3 - Longbow, too unmanuverable to me, it was Chuggy McChug. Only one turret for those nasties who were able to get on your tail (Every enemy at the waypoint) and was a general horror to fly, whenever possible I selected something else.
WC4 - Never played.
WCP - Shrike, my lord it was horrible. I dreaded flying those things, like all bombers, unfortunately they were unmanuverable, they packed alot of punch, but no sane pilot is going to go you head to head to let you use those weapons.
I personally loved the Arrow, Hellcat and Thunderbolt from WC3, loved the Excalibur too but the armour was dodgey.
Cheers