Which kind
I spent some time at the back of a nude hiking group and had plenty of chance to observe the bums. I produced a sort if identikit. Here are some pointers:- are there two dimples above the bum; dimpled or rounded sides; does it wobble once twice or four times with each step; a Y shape or I shape at the top of the cleavage; firm or not; wider or not compared to the shoulders; hairy or smooth. With this identikit we can put together a combination that fits every bum.
I have an affinity for curvy figures with well endowed butts. All asses have drawing power, I've never met an ass that I wouldn't want to cup and kiss. Give me an ass over 40 inches and I will always drool and dream of putting my face on the ass and spend copious amounts of time kissing and licking especially around the anus, I'd just be in asskissing heaven!