One of choices on their five lists sort of overlapped, so will make one big answer for that.
1/1: Original Characters from ficwize and non-Mary Sue-ish original female characters from sophiedb: What can I say, I adore creating OCs! It's part of what I enjoy about writing. I initially discovered how much fun OCs were back in the old Forever Knight days. A bunch of us on IRC created a character each, and then shared them amongst ourselves. That eventually became the 'Bloodties' series, which I still write all these years later.
So, the fun part, which leads into the necessity part. I'll use Highlander as my example, since it,along with FK, are the fandoms I've written in the longest and nearly exclusively in one form or another. I'm a Methos fan, and while I don't dislike Duncan, his character just doesn't engage me the way Methos does, and I don't really have the urge to write him all that often. We have Duncan, who has Amanda, and we have Methos who had Alexa, and then they killed her off. So the Methos fan who wants to read/write relationship fic pretty much requires an original character or two or three [g] I love reading such fic as much as I do writing it, and I really wish there were more OFCs in Highlander fandom. Alas, that's not likely all these years after the show has gone away.
All the characters I write are their own unique selves, and if they were real, I'd like to get to know better. In fact, I have a bit of a plot bunny where I would use some of my OCs from my different fic series and place them in an ATF verse M7 story. Instead of being immortals or vampires, they'd be mortal. It would bring one of my favourite, more recent OCs, Jacob Tanimura front and center. In my 'Bloodties' series, he's a former Marine who became immortal in Afghanistan. In this, he'd be a former Marine who wasn't killed and is now an ATF agent. I'd also have a mortal Charlotte, and Arianna Arnisen, who would still be married to Jacob, but not a vampire. The other cool thing would be that it wouldn't be a crossover, and you know how hard that is for me!
And last, but not least, the old Mary Sue thing. I think that term has lost whatever meaning it may have once had. It's just used now as a label against pretty much any OFC. It actually amuses me at this point in my life. Honestly, those that like to trot it out seem to think that the writer is going to be crushed and collapse into a weepy little heap. To that, I say pfffbbbbbbt!! I've been writing OFCs for nearly 15 years, and a few grumpy gus's aren't going to stop me now. Write what brings you joy and stay true to your own heart -- and let the chips fall where they may :) Life is too short to worry about what other people think.
Now for the rest of ficwize's five...
2: Crossovers - I just think certain characters from different fandoms need to interact. And in the case of Forever Knight and Highlander, it was almost canon. There was a crossover episode in the works, but they ended up having to shelve it. Now that would have been cool! I would much rather write LaCroix and Methos annoying each other than Duncan and Methos, or LaCroix and Nick, so I do [g] First gen story I ever posted was a story with Methos and LaCroix in it.
Some fandoms just fit together, and some just lend themselves to being crossed with others, as do certain characters. It's my own personal mental alchemy, and I have a blast doing it.
3: Magnificent Seven - My shiny new old fandom! I'm still not sure why I didn't see it when it first aired. I can only assume it was on when two other things were back in the old days of one VCR. Because I love Westerns, and I'd seen the movie and the original Seven Samurai. But better late than never! Let's see, I read strangevisitor7's story 'Ghost Town', which was an SPN/M7 crossover. That sort of tweaked my interest. (True story: I knew Ron Perlman had been in M7, so when I read that first story, for some reason, I thought he played Ezra. That's who I was visualizing when I read!). Then, Casey asked to borrow my OC, Charlotte, for an Old West fic she was writing, since in one of my stories, I had her living in New Mexico in 1867. About the same time, the DVDs came on sale at Amazon, and the rest, as they say, is history! I just love the characters, and the friendships. Friendship is a relationship I don't think we put as much importance on as we should these days. To me, a true friend is as important as family or a spouse/SO. I think back to the books that really meant something to me as a child and young adult, and it was the friendships that stood out and made a lifelong impact. Jo March and Laurie, Anne Shirley and Diana Barry, Jane Eyre and Helen Burns, Frodo and Sam, Legolas and Gimli, Merry and Pippin. So I'm drawn to books and media that portray those bonds, and M7 fits the bill in that regard. Plus, it's a Western, and the guys are cute, so what's not to like?
4: Utah - My new home state. I'm a fourth generation Californian, twice removed, I like to say. My great-grandmother was born in Grass Valley in 1865, then the family moved on to B.C. when she was a child. I have a deep and abiding love of my home state, but sometimes, you have to move on. We anted to live somewhere where we could afford to buy a home, and me and other family members have made many trips to this part of Utah over the last 15 years. My parents and brother moved here five years ago, and ninjababe and I moved here in January. This is the first time on my entire 40+ years I've lived in a home we own. It's kinda hard to get used to. It's affordable, the scenery is amazingly beautiful, it's central, putting us two hours from Vegas, four from Salt Lake City, and fivish to L.A. -- which is closer than when we were in Monterey. Especially good since we're Disneyland fanatics :)
5: Iron Man - The fandom that ate my brain! See, ninjababe drags me to comic book movies, and I go, I watch, and then I make her go see a movie I want to see in exchange [g] Then Iron Man came along. I hate her. I think part of what I like is that Tony's just a guy. Yeah a genius billionaire, but a guy. He has no special powers or radiation induced abilities. And he isn't whiny. Now that's a real plus. It has humour and angst and a very human hero. Plus it has the awesomeness that is Pepper Potts! I'm not sure if I'm going to like it when they get into the whole superhero board of directors thing, but I'll always have the first movie :)
Now on to Sophie's list...
2: Kittens - Kittehs, doggies, birdies, I love em all. I grew up in a hotel for the most part, and we weren't allowed to have pets. I think we've more than made up for it now. We've become something of a one family rescue unit over the last two decades. Sometimes, we find homes for our rescues, but most of them end up staying with us. I was saying to my mum how odd it is that whenever we loose one of the kitties, another stray shows up. There must be kitty guardian angels showing them the way.
3: CHEEEEEEEESE - I'd give up chocolate before I ever gave up cheese! And the smellier the cheese, the better! One of life's great pleasures is a fresh baguette, some cheese and a bottle of red wine.
4: Almighty Admin - Not sure what to say about this one? Maybe I'll come back to it :)
5: Sexy men of fandom :)- Methos, Jack Sparrow, Admiral Norrington, Ezra, Chris, Vin, LaCroix, Jack O'Neill, Dan Clifford, Colonel Montoya, Tony Stark, Mal, Mr. Darcy, Archangel, Magnum, Sonny Crockett, Sarek, Picard, Aragorn, Boromir, Avon, House, Han Solo. Will that do?!?