I'm not a "boob guy", but underboob is fantastic. I'd rank side boob up there too.
I think cleavage and the top of the boob get all the love because under boob and side boob are ridiculously hard to pull off without exposing too much, and you can't have a mediocre rack...
“Activism is a way for useless people to feel important, even if the consequences of their activism are counterproductive for those they claim to be helping and damaging to the fabric of society as a whole.” - Dr Thomas Sowell
Underboob is the internet musician of boob. You got to be good to be a successful internet musician; you can't hide your boob flaws behind push-up marketing and frilly bits of public relations when it's just raw like that.
That's why it gets underrated. Most women can't hack it.
"ATTENTION: Customers browsing porn must hold magazines with both hands at all times!"