The R 1250 GS is the 2019–2023/24 volume king of big adventure bikes: 1,254 cc ShiftCam boxer twin, about 136 hp, a 850–870 mm seat and a wet weight that starts around 249 kg before you add cases. It replaced the R 1200 GS (water-cooled 2013–18, oil-cooled before that).
Adventure and Rally variants raise suspension and seat height again. The boxer is the point: low centre of gravity, shaft drive, dealer network. It is not light and it is not cheap to tyre.
Compare with the Africa Twin, Multistrada V4 and Triumph Tiger 1200.