Not much not to like here Dave
I think the expressions make the photo, so you have obviously got something that is attracting their attention. Also it looks like the puppy behind the others is hiding/shy and is looking a bit wary. So there is the potential for any prospective purchaser to find some personality in the subjects.
Has he/she go a squint, or it is just the way you have caught him/her?
I like the framing and the hi-key treatment, but would look to remove the dark line on the LHS of the LH pup.
Can't make up my mind over the catchlght in one eye and not the other - but if I noticed it, maybe it is bothering me.
As I said - you can't go far wrong with puppy/kitten shots and the ones you have shown us do sand out from the average because you have taken the trouble to use a background and have told them how you want them to pose.
Have you found a way to remove superglue from fur?