I like how the first little guy looks like he's "posing" for the shot. Almost a mischevious grin going on there...
The last has to be my favorite though...there's an intensity, without...the almost wild/crazed looks that the other dogs seem to display in the other shots.
#3 hits a soft spot in my heart, that looks like a beautiful, happy dog. 4 is another that I really like, almost like the dog is sneaking up on the disk.