1. Consistency and continuity. I like to see characters that have consistent personalities but are visibly affected by the things that befall them. As someone who tends to play a lot of longish-lived PCs who age up from teenagerhood to adulthood, I love to see people RP the subtleties of aging, a personality that stays the same at its core but matures (or immatures!) over time.
2. Emotes that reflect a character's positioning in the world. Interacting with room descs, the weather, NPCs, furniture, anything like that. If you're a half-giant and you emote ducking under doorways and crouching in cramped rooms, you're probably gonna get a kudos from me.
3. Characters who hemote. It's not a requirement by any means, but catching a hemote during a scene when I didn't expect it is an absolute treat. I still remember the first time I ever tensely met someone in the wastes on my first PC, this terrifying mul who may have been a raider, may not, and he hemoted his hand twitching toward his belt before he actually drew his weapon. That took an already-tense standoff into PUCKER FACTOR ELEVEN HOLY SHIT. It was like reading some particularly potent foreshadowing in a book that gives you this horrible sinking feeling.
4. Everyday average commoners played well. I've played some pretty snowflakey shit in my day and enjoy a good high-magick high-intrigue plot, but the core of my Armageddon enjoyment is dusty mundane average people against a world that impossibly outmatches them. I love simple scenes: cooking, hunting, hunkering down against the wind in the wilderness somewhere, Byn chores.
5. Fear. This is totally self-indulgent but if you act afraid of my scary characters, I'll remember you fondly forever.
Nothing against people who don't as I assume every PC has their reasons for acting how they do, but people who quake in their boots when book-quakey shit goes down are good people.