I don't design characters too often, but the first thing that I usually think of when designing them is their personality and what kind of role I want them to play, though primarily personality. I usually end up thinking to myself at one time or another of an idea for a character and how they act and what they're like and go from there. After that I come up with an idea of what kind of role they play in society, along with the species and gender and then appearance and powers. Also jobs. I always give my characters actual jobs in every rpg I ever play, even if it's only in the backstory, though what counts as a job is stretched at times.
Sometimes though I just make a character for one reason and then they develop or don't. I originally made Yasurek during the first reboot, though in that case he was just made because I thought that having a character that was an actual everyday koro guard was somehow subversive and interesting. In this reboot I took the character and shifted him into having retired from his job because there were openings for the Infernavika crew and I had spent a lot of the last reboot reading Lohkar and Kalama's adventures together, meaning that I kind of rushed through transferring him over.
As for how connected my characters are to me, it's a grey area. When I make a character, I try to keep them separate from me but still having some aspect of myself inside them so I can at least connect with what I'm writing personally on some level. Unfortunately, they often seem to drift into becoming more like me as I write them.
In hindsight, Yasurek was always like me on some level. Early on, he was my insecurities with the rpg and lack of confidence, trying to fit in within a crew of people that he had never hung out with before, trying to find acceptance. Then he developed a severe depression and lack of self worth about the same time I did in regards to the rpg due to having one of the worst impressionable lurking rpg phases ever in terms of what parts of the rpg I was reading. This carried over to all of my characters and even the impossibly happy character became a somewhat comical voice of my inability to accomplish anything. I eventually managed to develop him out of this with the help of Ghosthands, and now he's become a snarky individual always looking out for his friends and guiding them towards the more moral path, which is now a bit too much like me, which is probably why his dialogue is so easy to write.
In terms of all my characters, in spite of their developments and differences, they'll will probably continue to inherit my aversion to rpg combat. When I make my character's power sets and abilities, about one half is on the cool ideas side of the spectrum (teleporting le-toa archer) and the other half is more to create an interesting contrast (The impossibly happy earth toa has a mask of stealth, the plasma toa fisherman with a kaukau). My characters will always be at least competent (in their profiles anyway) so that I will have the ability to force them out of combat situations if they get caught in them (unless both characters are controlled by me, in which case they will actively not be near other player's characters and nothing ends up happening that affects anything in the long run).
As for my favorite, it's probably Yasurek. Not first reboot Yasurek, he didn't do anything except chase a toa who escaped with ease, but new reboot Yasurek. To me, he represents in some ways how I've developed as a writer, in that he has become a somewhat 3-dimensional character who has accomplished something in the rpg (i.e. developed at all). He's also my favorite because he's the only one that managed to keep having a plot to be in due to being a part of the Infernavika, despite being the inactivity-sinkhole that it is. In that way, as long as the other crew members keep having things to do (Lohkar in particular), Yasurek has stuff to do, and I have an rpg character to write and participate with. Without Yasurek, I'm just a newbie lurker, despite having been on this site for several years and in this rpg for a few years. With him, I'm a newbie rpg player despite having been on this site for several years and in this rpg for a few years.
In summary, my characters don't really develop unless I develop psychological issues and work through, my characters almost always go nowhere because I come up with roles and personalities with no plots for them to actually follow, and they always end up being somewhat snarky heroic characters that are nice despite the darker and edgier nature of the rpg who don't do anything of importance, except the one who went through the most severe bout of depression and went around asking other characters what his role in the story was. Note how I never said my character designing process was an actual good one.