I'm listing a lot of fandoms this year bc I've been slowly breaking up with Marvel for, like, 2+ years now and haven't found a replacement fandom, I just keep trying all the fandoms to see if one will stick. Here's what I've been into lately, in no particular order.
X-Men (First Class movie 'verse): My main pairing is Charles/Erik, though X-Men Apocalypse made me yearn for Charles/Erik/Raven. I specified First Class, not because it has to be based off that single movie, but because I don't actually enjoy rivals pairings normally, so the early 2000s Charles/Erik is less interesting to me, than the closer relationship we've seen in First Class/Days of Future Past/Apocalypse. I'm not opposed to stories that are set in the earlier (later, in canon) movies, just it's a bit more hit or miss how their relationship is portrayed. My favourite tag in the fandom is Alternate Universe - Still Have Powers because I love stories that explore how the world would react to mutants and the powers that they have but the actual canon is so intense, goes to such an extreme. These AUs generally have more of a middle ground.
Marvel Netflix (without a focus on Frank or Danny): Daredevil is the netflix show I've been the most fannish about in the past. Ugh, my stupid avocados, and the awesome women! I'm not really a Frank Castle fan though and the only spark of interest I felt around him was his relationship to Karen.
Jessica Jones and Luke Cage are also awesome, though I haven't delved into those fandoms as deeply. Iron Fist... well, I mostly don't understand why they felt the need to make that show. I didn't hate it but I didn't love it like the others. I won't object if you do a Defenders podfic that has Danny present, but I'm not going to enjoy a Danny-centric story.
Marvel comics 616: I'm mostly interested in Steve/Tony centric stories from comics, though Jan is my fav Avenger, so anything with her in it is amazing! I also have some recs on AO3.
MCU: My main pairings from MCU are Steve/Tony, Clint/Coulson, Clint/Coulson/Natasha, occasionally Tony/Bucky or Steve/Tony/Buck that isn't centered on Steve.
For Steve/Tony, I prefer the stories that build off the comics canon for their relationship (because I admit they are not the strongest pairing within the movie canon). I cannot deal with Civil War stories (from the movie 'verse, 616 is a different matter). My Steve/Tony MCU recs (these are pretty sparse)
For Clint/Coulson and Clint/Coulson/Natasha it's all about the competency porn for me. I love Strike Team Delta, I love them watching out for each other, I love them supporting each other, and I love them kicking ass together. My Clint/Coulson recs
Iron Man: Armored Adventures and Avengers: Earth's Mightiest Heroes
I've watched and love both of these cartoons, and would happily receive gifts from either of these shows. EMH has the same pairings as the rest of my Marvel preferences, but also includes Clint/Hulk. AA I ship basically Tony/Anyone. :P
Moving out of Marvel...
My main pairing for this fandom is Kala/Wolfgang, though I love all the canon pairings (including Sun/Mun and Capheus/Zakia).
Beauty and the Beast (2017)
God I really wanted to throw myself into this fandom after I saw the movie, unfortunately the fandom is not that large. ;__; I ship Belle/Adam and have no interest in seeing Gaston redeemed, nor am I into Lefou pining after him (it's fine if it's present in the story like it was in canon, but I don't want Lefou pining to be the main point of the story)
Star Trek AOS
I blame Rjcreighton for this one. I've pretty much just done Kirk/Spock in this fandom. I have a few recs on AO3 but they're mostly really long stories so probably not useful here.
Merlin/Arthur is my main pairing, but I'm also 100% there for canon-era slice-of-life gen, or stories of how awesome a queen Gwen was, post-show. Canon-era stories tend to be my fav, however I'm fine with AUs that take place in a different time so long as there's still magic (there are non-magical AUs that I like, but they can be more hit and miss for me, if you find a modern day non-magic AU that seems to really align with the likes I have listed below though, go for it). I tended to enjoy the potential of season 1 more than the reality of the later seasons, I'm totally there for redeemable Morgana. I have a bunch of (old) recs on my pinboard.
Oh Mark Watney you poor goober, look what Mars has done to you. I primarily read gen in this fandom and enjoy Mark trying to cope while everything goes wrong. I'm also ok in reading pairing fic in this fandom but don't have any particular ships, the fandom skews to Mark/Beck, which I'm fine with but don't feel any great love for either. If you go the way of shipping I'd probably prefer something where it's either background or actually puts some work into making me get behind the pairing.
I fell in love with the franchise through Terminator: The Sarah Connor Chronicles and I adore Cameron. I also have a thing for people growing into heroes so love John Connor's characterization from SCC and T3. My ships are John/Cameron and John/Kate, though this fandom is the one I read the most gen in. I also adore crossovers with Terminator. If you can find good crossovers with this and any of the other fandoms I've listed, that would totally make my day. My Terminator recs are on my pinboard.
Things that I love (an incomplete list): Rule 63, identity porn, competence porn, trans characters, world exploration, found family, pretend dating (really, most harlequin-type storylines), angst, AUs, origin stories, power dynamics (including D/s and BDSM), emotional punches in the gut, and way more than I can think of at the moment.
I don't have many no go zones but cannibalism and killing people in a fetishized way are really hard stops for me. Related to the previous point, I mostly can't deal with zombies and am finding vampires harder to deal with too. Detailed gore on a large scale also makes me queasy and I'm not a fan of horror.
I don't enjoy stories whose plots are driven by homophobia.
As mentioned above, I'm mostly pretending that Captain America: Civil War never happened and tend to immediately back button out of anything that deals with it.
Note: Since these are things other people usually list as no gos, while I wouldn't necessarily say these as things I love, I don't mind unhappy endings and/or death fic. Related to my like of emotional punches in a gut, I like when a story can make me cry. I don't mind sad events or endings so long as the emotions ring true. So if you have a story that you think would work that has an unhappy ending or character death, go for it! I am well known as an angst muffin after all.