What is the 0xFF supposed to do?
No local community on https://www.thethingsnetwork.org/community?
Did you see ttnmapper.org? (That only shows results of people who go out mapping explicitly, but may give you some idea.)
Aside: note that thermally insulating glass will affect reception too, so go outside when testing the range.
Such list shows what others are using, but unless the majority is using ADR it doesn’t necessarily indicate which settings are needed for proper reception? Other factors, most importantly battery life and the TTN Fair Access Policy will affect a proper choice too?