Actually, all three. Maybe your experiences are different than mine as I am a recreational rider and have never raced or worked as a bicycle mechanic.

I have seen all kinds of fit criteria - including straddling the top tube, seeing if the handlebars hide the front hub when riding, placing your elbow on the saddle nose and seeing if your middle finger reaches the stem, etc. - but none of these methods gave me a proper fit. In the 80's the Fit Kit was the newest most scientific thing going, but even it didn't recommend a comfortable fit. The shop I go to has been building custom bikes for over 30 years and has compiled their own fit data and uses this fit bike to ensure that you are comfortable on your new bike: