Katie Holmes vs. Jennifer Aniston -- FINAL BIKINI WAR OF 2013

This is it ... the last bikini objectification of the year ... and so, we proudly present -- KATIE HOLMES VS. JENNIFER ANISTON!!!!

Katie was out in Miami, flaunting her post-Tom Cruise physique in a hot pink 2-piece.

Jennifer is still in Cabo ... hangin' out with her man Justin Theroux.

Two hot bodies -- but there can only be one winner.

So, we gotta ask ...