All Gummed up Inside Orchestra

As u all know i ship FinnXFP so u know that Flame Princess is the one i would pick... but i have reasoning behind my pick besides the obvious "i want them to be together." of "they're so cute as a couple." reasons that everybody uses.
i will back up my claim with reasoning and discredit the other choices with reasoning. first i will discredit.

Bubblegum: now most people like to use the "she's too old for him" reason but that's not a very good reason because when finn turns 18 then age is no longer the issue. Finn is either 14 of 15 now and it's only a few short years before he catches up...

(From part one, Finn, the Knight of the Order)

‘Finn and Marceline awaken to an alarm clock, still entwined in each other’s arms. It’s 7am on the Island of Order. They both rise and kiss passionately, and then prepare for the day. They both still have vragen that need answers! As they finish getting dressed, the bracelet gegeven to Marceline begins to pulse. She raises her arm and a holographic image appears. Finn and Marcy both see the very concerned face of Angel Abadeer. “Good Morning to u two. I wish we had meer time to chat but we found out what the Lich was up to. He used the...