Yikes. I have a bunch of favorites, including a 1970 Honda CB350, a 1976 Suzuki GS-750, a 2004 BMW R1150R, and a 2006 BMW K1200R.Someone posted this topic over on the Garage Journal and it was pretty interesting. Lots of trips down memory lane. No specific criteria; just the bike that was your favorite.
My current favorites are a 2020 Triumph Bonneville T120 and a 2023 Suzuki Hayabusa.
Still to come if I live long enough is an Indian cruiser of some kind. I can't croak until I've owned a V-twin.