Most prone to preening
I believe the answer is:
vainest
(Other definitions for vainest that I've seen before include "Most egotistical" , "emptier than all the others" , "with lowest hopes" , "least humble" , "Most conceited" .)
I believe the answer is:
vainest
(Other definitions for vainest that I've seen before include "Most egotistical" , "emptier than all the others" , "with lowest hopes" , "least humble" , "Most conceited" .)