A FlyerTalk Posting Legend
Join Date: Sep 2012
Location: SFO
Programs: AC SE MM, BA Gold, SQ Silver, Bonvoy Tit LTG, Hyatt Glob, HH Diamond
Posts: 44,333
I don't know how you're counting the 15/10, but I don't think it's accurate.
AC seems more confident in their ability to sell the BNE seats, but it's pretty early to offer advice given that they're both P0.
PY will definitely put you much higher on the upgrade list, and it's a decent fallback if your upgrade doesn't clear. I would never personally waitlist from Flex on an intercontinental flight. Either I can confirm the upgrade at booking, or I'm buying PY.