No headphones jack.
Most people use bluetooth devices nowadays. Few have wired headphones, which they can still use by using a €2 adapter that you just leave plugged to them all the time. Then there is a 0,1% that complains on the internet demanding that phone companies keep a extra hole on their devices for a specific purpose another hole can already do. Oh and HMD phones don't have it either, at least for what i could find.
More repairable
They seem about the same (glass, back, speaker, battery, port), but on the ff5 you can replace the cameras as well.
more flexible
Tf does that mean? You can bend it?
long term support and updates.
Liar? Fairphones have like 8 years of security updates and major android version upgrades. HMD gives like 3 years on their latest devices... What are you talking about?
Cheaper too.
I'll give you that, but it really ends there.
HMD phones are not a bad choice at all but if the affordability isn't first in the list I don't see how they would make a better purchase over a Fairphone.