Do you have a favorite language that you've created? If not, what's your fave thing about each one?

That’s a big question. If I had to choose one, it’d either be Irathient or Kamakawi, but that’d be leaving so many out. So let’s see, favorite thing about each one (in no particular order)…

Irathient: Definitely the noun class system. It came out just the way I wanted it to.
Castithan: The writing system. (Not the look of it, per se, but the combination of the look, the evolution and the way it’s used.)
Kamakawi: Also the writing system. One of the most complex things I’ve ever attempted and pulled off in a conlang.
High Valyrian: The verb conjugation system. Difficult, but worth the effort.
Dothraki: The case system. It’s far simpler than something like High Valyrian’s, but I like the way it works. I have a better grasp of how to manipulate that case system than I do any other system, natural or constructed.
Indojisnen: The flexibility of the system? Is that a copout?
Shiväisith: The case system. It’s big and silly. I love it.
Sondiv: The nominal system. I finally got the chance to do it right, as opposed to in…
Megdevi: …where I did the triconsonantal root system totally wrong (though, as far as I know, it was the first actual attempt to ever reify such a system in a conlang. The only thing close was Rick Morneau’s essay on how one might utilize such a system for an auxlang, but he never actually created such a language). I guess my favorite thing is the writing system, though, since I still use it for taking personal notes.
X: The tense system that allows you to build weather into it simply as a natural outgrowth of the system.
KNSL: Pronominal subject/object incorporation (or agreement, depending on how you analyze it).
Kelenala: If I were ever going to learn to actually use a language, it’d be this one. I still love my old super creole.
Lishepus: The crazy derivation system (both nouns and verbs).
Zhyler: The noun class system. It’s not super great, but it was influential on future languages I worked (especially Dothraki and Irathient).
Astapori Valyrian: The sound of it. As spoken by Jacob Anderson. Who is a golden god.
Sathir: These little stories I came up with. Also that I figured out early why infixing doesn’t work as a form of inflection without a full evolution behind it.
Njaama: The sound of it and the tonal system.
Sheli: The tone system (which I still thing is at least semi-legit).
Gweydr: The stone script.
Epiq: The case system (the first one I did in a way that was even close to approaching correct).
Tan Tyls: The system of phonological epenthesis (not deletion), which was inspired by my wife’s master’s thesis on Potawatomi (which is an awesome language).
Sidaan: The evolution of the Philippine-type system (something I may revisit soon. I discuss it here).
Aaalis: The phonology, but also the font, which was a huge learning process for me—and ended up being the basis for all my modern fonts (i.e. the coding aspect of it).
New Project A: The verb system.
New Project B: The sound of it (though unfortunately this project will never see the light of day, I’ve learned).
Mbasa: Never made it very far, but I loved the phonology.
New Project C: The semantic dualism, which is almost comical. This one was a lot of fun.
Wivoys: I liked the writing system. It was a fun idea.
Skroth: To the extent that this even counts as a language, I like the sound of it, and the concept of an almost Nordic-like creole (not a posteriori, but in its sound).
Asshai’i: This one kind of had an idea that I repurposed for New Project C. I did it better in the new one.
Tetrect: Come on! Who wouldn’t want to play this game?! I swear, no one was excited about this idea but me…

Dai: My first noun class system.
Yanga Kayang: Everything. Defiance people: PLEASE let me do this language some time during the course of the show!
Fanglutsen: Absolutely, positively nothing.

Anyway, there you have it. Not all of these projects achieved any real girth, and most of them aren’t worth looking at ever again, but that is, to my knowledge, the full list of languages that ever achieved any type of critical mass. (The only other two projects I can think of never really got past page one.)

Incidentally, this is what it’s like being a conlanger. You start out thinking you’re just going to do the one language, but then you add another… And then another… And then another… And pretty soon you’re up to your ears in fabergé eggs. It’s supposed to be something you do on the side, but then it just takes over! It’s no coincident that both “conlanger” and “Cookie Monster” begin with the letter C.

Thanks for the ask! Fun trip down Memory Lane. Seems quite appropriate for my birthday. :)