The Portrait, when compared to the others is obviously the more serious of them, and it also fits well with every avatar compared to the Skeleton which looks deformed on most of its poor victims. It also has an ethereal vibe to it which is less comedically appealing but more Thirteen worthy.
2. Ghost
The Ghost was great for me because when I first saw people with nothing, I had a brief feeling of disappointment before I was pleasantly surprised by a ghostly jumpscare. The ghost works well because it doesn't rrly on avatars, replacing them entirely with a spoopy image.
3. Clown
Similar to the Ghost in pleasant surprise, and also relevant considering the hype for "It." In cinemas. It's also mine, so that's a bonus.
4. Axe
Simple, Halloween-y, wholesome goodness.
5. Spider
Not good, but at least it adds something rather than ruining it.
6./7. Red Eyes/Blood
No, I definitely didn't use MS paint....
8. Water
Wtf. This isn't even Halloween-y. I agree with other people, you waters are Randomize's rejected users.