Walden has at least four distinctive kisses.
The usual being the "peck". It's administered to Louis and Alan alike; usually in the morning while walking into the kitchen and following the smell of breakfast. A small kiss placed in their hair.
The "tentative kiss" which is usually given in public. Light because no matter how many times Alan says he's okay with it he always second guesses himself. This one is Alan's favorite because it means that Walden is okay with him no matter where they are.
Running a close second, however, is the "heated kiss". Kisses that communicated desire, led to desperate rutting and ended with them lying in a sweaty sated pile.
Then there's "the kiss". Alan can't even use a word as mundane as "favorite" to describe it. They varied in length but the intensity was always the same. They may lead to slow love making but it's far from a requirement. They're kisses of reassurance; that things are as they are. Giving thanks to whatever allowed "them" to happen.
Four kisses and Alan loves them all.