I also adore all dogs but here are some I find to be the prettiest.

Pit bull terriers
American Bulldogs
American Staffordshire terriers
Staffordshire Bull Terriers
Bull Terriers
(all bully breeds really!!)

Catahoula Leopard Dogs

Siberian Huskies - all huskies really!

Border Collies
Australian Shepherds
all hounds! especially beagles, coonhounds, and basset hounds

Labs - all of them especially the black ones!
Goldens
Collies
Corgis
Dobes
German Shepherds
Giant Schnauzers and the standard ones!
Newfoundlands
Rotties
Rhodesian ridgebacks
St. bernards
Shiba Inus
White German shepherds

and all mutts. I really adore them all!