John Legend vs. Justin Bieber WHO'D YOU RATHER? (REARVIEW EDITION)

7/8/2015 7:21 AM PDT

It's a battle of the buns.

Here's Chrissy Teigen's glute-gloat of her 36-year-old husband John Legend (left) ... and the Bora Bora bubble 21-year-old Justin Bieber blasted out on Instagram earlier this week (right).

Put an end to the debate.

The question is...