I recommend the rx100m3 as the starter rx100 because
It starts wider at 24mm (ends shorter at 70mm, but you can easily crop to get same as 100mm end of m1 version).
It has darn good Image Stabilization, so when it defaults to 1/30th, the stills are not blurry. Note: handheld, many of us could not get blur free stills with the rx100 because it's IS was not good.
It has auto iso in M.
tilt lcd and pop-up evf are terrific
of all, if affordable, I recommend the rx100m6, it's apparently 'dark' lens is effectively brighter because it has even more effective image stabilization (I can shoot m6 handheld at 1/20th), and you can successfully use ISO up to 6400. It's in-camera Noise Reduction (JPEGS) is very effective.