Edison thinks all human beings are YUMMY. Every time we lie on the floor to stretch or whatever, he comes by and promptly gives us a doggy facial. This is much more vigorous if we've been exercising, so our current hypothesis is that he likes the skin salt. He's also fond of certain lotions and creams I use, and will go after my hands and face after I've been moisturizing. :)
Ragnar is a kissing bandit and he's especially obsessive in the morning. I'm at the tail end of a really bad case of bronchitis, and it's made us joke that he thinks of me as his puppy. Every time I have a terrible coughing fit, he's in my face to clean me and make sure I'm going to live. It's very sweet, really--he looks so concerned.
Kelso is getting more licky--probably just out of competitiveness--but he's more polite. He gives gentle little licks instead of great sweeping full tongue ones.
Aber will only lick the very tip of your nose if you've done something he deems extremely worth rewarding. He certainly doesn't fit any sort of corgi model of licking, although he does have a fabric/upholstery fetish and will lick that for seemingly hours on end.