Both West divisions in the NFL have been called the worst divisions in football at some points over the last few years. The AFC West hasn't had a legitimate contender in a few years (outside of the San Diego Chargers, at times) and the NFC West had the 7-9 Seahawks win the division last season which tells you their perception around the NFL.
But, as ESPN notes (via PFT), the AFC South has the worst winning percentage outside of the division this year. The NFC and AFC West come in with the second worst record outside of the division at 18-22. The Jaguars and Colts contributed heavily to the AFC South's record and even the division winning Houston Texans don't look too hot at the moment.
Every Week 17 game is a division game so those are the season's final numbers.
And, as you could guess, the AFC and NFC North, comprised of potentially five playoff teams, have significantly better records than the AFC South and both West divisions, ranked No. 1 and No. 2 in the league.