Imho all tilesets are pretty equal when it comes to eyecandy.. but some of them have bad masking and usability so I shall rate for that..

**** has bad usability. It lacks certain very important tiles, which make it harder to do what you want with it. (and you often need layers to correct them)
Psych lacks a few semi-important tiles, making it harder to make the eyecandy flawless.
Colon - talking about usability.. and bugs, cough
Medivo - masking bugs..
Labrat - some missing important tiles. incompleted
Beach - usable?
Castle - lacks one unmasked layer4 bg tile making some things harder.

I want to comment, the jj2 tilesets are awesome! They are perfectly cartoony.