Main thing for 10 is..
Is this a joint mortgage? Relationships end. The penalty to leave within the first 5 years will likely be 5 percent.
Do you plan to move in the first 8 years? Makes it difficult
I'd agree with the rate bit. The next LTV bracket in my case isn't worth worrying about vs rate rises falls.
Fyi. If I was single or sole party on mortgage I'd have gone with 10 year.
It is a joint mortgage and the house was purchased largely because it gives us access to an incredible secondary school for our son. Since he's only 2, this is a 15+ year house for us.
Having been through it once before, I'm well aware that relationships can and do end. However, if I lived my life as a pessimist about everything, I'd never get out of bed.