Embrace the new school geometry.
For general riding (trail, XC), reach should be dictated by stem length, not seatpost layback. I think with the advent of long, low and slack geometry, the fad for “sizing down” (i.e. 6ft+ lads on medium frames with long stems and loads of layback, cuz its chuckable innit!) is a thing of the past. If you are into more aggressive riding and feel more comfortable with extra standover, I’d be looking at frames with a sloping top tube rather than sizing down and running loads of layback on your seatpost.
However, I know Specialized full sus bikes are based around a layback post (its either 2cm or 2.5cm). Use an inline post and the effective seat angle becomes less slack. Hence the fact that their own dropper post comes in layback only. I ride a Specialized Camber and if I use an inline post then I get bad knee pain as my pedalling position is all wrong. Something to bear in mind.