One True Foursome: I ... don't think I've read very many foursomes, that I remember?
One True Threesome: KJB right up there! Though Bruce/J'onn/Wally came as an odd but welcome surprise. And from my HP days, Sirius/Remus/Severus. And Kyouya/Tamaki/Haruhi, because I can't stand to break up any of the pairs. And I did see one Doctor/Brig/Doris story, somewhere, that I remember flattening me.
"Canon" ship: Londo/Timov. Casey/April. Bruce/Selina. Clark/Lois, because the woman is kickass! J'onn/My'ri'ah.
"Not quite canon but should be" ship: This what I believe should be canon? Bruce/J'onn, which I still think could really happen. Either Avon/Cally or Avon/Vila. Tatsumi/Tzuzuki. Harry/Ramirez is plausible, to my mind. Harry/Marcone would take some work but I want it, dammit! Any of the Kirk/Spock/McCoy triangle would be believable, and personally I want S/Mc. And Scotty/Uhura, oh yes! And Picard/Q totally happened!
"If this happens I'll stab my eyes out with a spork" ship: Spock/Chapel. I did not like! And Bruce marrying anyone that isn't J'onn or Selina. Clark is married to Lois in canon, and I would hate to see that marriage actually break up, slasher tendancies or no. Cain/DG.
"You are one sick bastard" ship: This where I'm a sick bastard? Because in that case ... I have a fondness for Donnie/Bishop that I don't think many people would approve of. Also, I wanted more Odo/Garak fanfic. And I shipped Basil/Ratigan, and mouse/rat slash, in a Disney movie no less, is perhaps a step too far for many.
"I dabble a little" ship: Everything. Literally. I'm extremely leery of incest, but even that I've read once or twice. I dabble in everything.
"It's like a car crash" ship: P/Q can go so incredibly badly wrong. Sirius/Severus likewise. And Doctor/Master, especially towards New Who, is so frighteningly angsty and tragic and self-destructive. But then, that's Ten anyway.
"Tickles my fancy but not quite sold yet" ship: I'm not sure what's meant here, but hey. Never stopped me before. I like Bruce/Shayera, but I really only flirt with the idea. J'onn/Wally intrigued me, but it needs more work. Glitch/Cain, because I'm not sure I actually ship *anyone* in Tinmanland, but they could so work.
"Makes no canon sense but why the hell not?" ship: Alfred/J'onn! Totally! Also, Avon/Travis.
"Everyone else loves it but I just don't feel it" ship: I never really got Bruce/Diana. And I'm not fond of Avon/Blake
"When all is said and done" ship: As in, when all is said and done, they'll always have each other? Whether they want to or not? Londo/Timov. Londo/G'kar. Clark/Lois. Picard/Q. Bruce/J'onn. Avon/Vila, right up to the death.
"Guilty pleasure" ship: Avon/Travis. Selina/Lois. Bruce/Clark, whenever I think of Lois, and in this regard I'm very guilty indeed. Bookverse Harry/Morgan.
"I can't believe I've read it and liked it" ship: I once read a Wormtail/Wormtongue crossover fic. And liked it. I don't think anything else quite tops that one.
Favourite older/younger ship: J'onn/anyone counts, and my fav is definitely Bruce/J'onn. And Q is several billion years older than Picard.
My first "I could never abandon you" ship: My first ever ship was Severus/Poppy, and I love them still.
Favourite devotion ship: Javert/Valjean. Grantaire/Enjolras. S4/5 Londo/G'Kar.
Favourite never-met ship: Lots xover ships here. I like Seven/Avon. And I read one Master/Drusilla(Buffy) that was utterly chilling and utterly perfect.
Favourite "Awww!" ship: Picard/Q, done schmoopy. Kyouya/Tamaki. April/Casey.
Favourite perverted ship: For me this usually entails villain/hero/other ships. So. Basil/Ratigan. Aladdin/Jafar. Bishop/Donnie. Master/anyone, but most particularly Master/Jo, which I've seen done fabulously once or twice, though damned if I can remember where. Ivy/anyone, because my mind keeps going irresistably towards the vines/sex-pollen combo, with the occasional detour to nettles and orchids (look, my mind is not a pleasant place, sometimes, alright?).
Favourite dominence!battle ship: Master/Doctor, except not Ten/Simm, because I don't like Ten. Kal/Bruce can venture into some lovely areas in this regard too. Harry/Marcone and Harry/Morgan probably count. Javert/Valjean is more Javert attemping domination, and Valjean rebuffing him but not attempting to assert it himself, but it probably counts too.