Yeah as a whole Who is way too unwieldy a fandom, I can totally do Third Doctor era:

M/F OTP

Mike/Jo, pretty much. If you’ve never read Speed of Flight by Paul Leonard I highly recommend it, it has tons of shippiness for them (also Mike angst).  There’s a bit at the beginning where Bell and Benton have set Mike and Jo up on a blind date together and it is just the most precious thing.  But they are kind of a sad doomed romance.  I LIKE THOSE.

M/M OTP

Fitz/Mike WAIT THAT’S NOT ACTUALLY A THING Brig/Mike but also in a way where it would never manifest as anything and even if they did get together it would be incredibly unhealthy, let’s be honest.  Basically my headcanon involves Mike pining away for the Brig who is clueless.  Also, straight.  Also, his commanding officer.  Also, kind of mean?  Like I know the fandom enjoys picking out the BROMANCE bits of the UNIT era, and the Brig being wry and lovable in later years, but there’s also quite a bit of the Bring being Not Very Nice to Mike, and sadly I can see him being the kind of guy who’d fall for people who are not very nice to him. :/

F/F OTP

This is harder because it’s a bit of a sausage-fest, isn’t it, Third Doctor era?  Honestly I don’t have one.  I could fish around and invent a pairing, but there are none that really present themselves.  WAIT DOES OLDER JO / OLDER SARAH JANE FROM SJA COUNT?  Because I ship that like a fucking armada.

OT3

If we’re speaking romantically, don’t really have one.  I’m pretty picky about three-person pairings and it has to really seem like it would work, to me.  I guess Doctor/TARDIS/Bessie.  Yes that sounds about right.

BROTP

UNIT, basically.  God I’m such a sucker for narratives about TEAMS. TEEEEEAAAAMMMM.  Someday I’ll inflict Best of the Best upon all my followers and then you will understand my weird references.

Favorite Canon

Again, I’m assuming that this is talking about pairings, so I’ll say Mike/Jo again, and now switch to recommending ‘The Switching’ which was a short trips and also there’s an audiobook Big Finish version of it?  And there’s some pretty adorable Mike/Jo stuff in there.  I should copy down the best bits and post them as quotes….

Favorite Crack

Wait, how are we defining crack pairings?  Does it necessarily mean an amusing pairing, or just an unlikely one, or both?  Is it just things that you know are not anywhere near canon?  I am bad at fandom apparently.  Uh.  Guess I should just make something up on the spot, I don’t tend to gravitate towards this sort of thing on my own. Let’s say Liz/one of the Silurian ladies from series 5. Yep.

OH OH NEVER MIND I’VE JUST THOUGHT OF ONE although I don’t know if it counts as a crack pairing since it was TOTALLY ON in one of the novels.  There’s one called Deep Blue where it’s Mike post-Green Death but pre-Invasion of the Dinosaurs and he runs into Five, Tegan, and Turlough, and the amount of Mike/Tegan in there was just UNREAL.  THEIR EPIC TRAGIC CONTENTIOUS ROMANCE.  Another one I need to post quotations from because y’all. have. no. idea.  So I ship Mike/Tegan PRETTY HARD as a result, and that’s pretty cracky, right?

Guilty Pleasure

…..I may or may not have quite a few of these.  A few of my headcanons definitely involve some unfortunate amounts of General Finch / Yates but I don’t talk about that a lot because then people start to realize I’m a pretty sick individual.  Uh.  Also Master/Mike, for the same reasons.  Benton/Bell (is this a guilty pleasure or a crack pairing?) and in my horrible headcanon the reason she just disappears from UNIT is that she DIES HORRIBLY.  I should probably stop talking now this is more of a glimpse into my brain than anyone probably wants.

Pairing I dislike/don’t understand

Yates/Benton, which is hilarious since it’s the only pairing I’ve written for this era?  I don’t know I guess I am strongly in the camp of thinking their relationship is platonic.  Very strong, and very important, but with no dick touching basically.

….Yep.  There’s probably more I missed that didn’t fit in any of those categories.