This one's difficult given that there aren't all that many things I actively like about myself as opposed to "don't actively dislike," but here goes:
1) My long hair. I'd like it to be (much) thicker and a less drab/mousy color, but it's conveniently inexpensive (I can cut it myself) and I enjoy having it long.
2) My height. 5'6" is a pretty good height to be. Not too tall to buy jeans and things off the rack, not short enough to need to wear petites. As someone with a 5'11" sister and 5-foot-even girlfriend who both suffer from height-related clothes-shopping woes, I appreciate the value of being average height.
3) I read very quickly. Sometimes this is a disadvantage (I can blow through the entire fic output of the average small fandom in a weekend, which is one reason I prefer longer fics) but usually it's useful. I can also read a book and walk (down the street/down the Manhattan sidewalk, to work, down the hallway at school back when I went to school) at the same time. I've been doing it on a daily basis for twenty-plus years and only rarely run into things, and most of those things are right-handed people who dodge right while I'm trying to dodge left.
4) I can write poetry in iambic pentameter (whether it's good poetry is debatable but at least it scans properly), and, probably relatedly, am really, really good at filking, including making up filks off the top of my head. I rarely use this for fannish purposes, except for very occasionally on f_fa, since filk isn't the fannish mainstay it used to be. Mostly, I use my filking skills in the time honored family tradition of changing the words of songs to make them be about my pets (I learned my filking skills at an early age from my father, who used to change the words of commercial jingles in order to sing them to the dog). In addition to deliberately teaching both cats to come when I whistle, I have accidentally taught one of them to come running whenever I sing the candy factory song from Chitty-Chitty Bang-Bang.* I have vowed to use this power only for good. (As opposed to "whistling means I'm going to feed you," which I have used for nefarious "I lied - we're taking you to the vet" purposes before and will again)
*For the curious, the sickengly twee magic cat-summoning chant goes thusly:
"If you are unhappy with dogs small and yappy
and cats who are cranky and mean,
If you seek perfection in love and affection
then there's something new on the scene!
A cat full of cheer!
A pet without peer!
Of purring perfection extreme!
From his giant pink ears
to his freckle-y feet.
A puffable, lovable treat!"
The cupcake you cuddle
Whose love is complete.
The cat who's incredibly cute!"