I am not certain it’s right to vilify Miles & Less.
It must work for some people, otherwise the reasons for retaining it would not stack up.
Personally, I shied away from Star Alliance loyalty until I earned, almost by accident, a top tier elite card flying shorthaul and found myself with several hundred thousand miles to burn. As star carriers historically offered slopey beds in longhaul business class (though I am pleased to say this is slowly now changing), First really was the only tolerable option; and on most of the carriers I sampled it was actually rather good. However, they have gradually ramped up the number of miles required for such jaunts, physically reduced the numbers of seats in the cabin, or in some cases such as Singapore’s Suites or Lufthansa’s First class these are blocked altogether except for their own frequent flyers. So it’s not that easy to redeem those miles.
Oneworld is great if you travel transatlantically, to Australia and within Europe which fits my usual travel patterns. Star is better for the far east (and Australia if you don’t want to travel internally once there). Oneworl still offers more flat beds in Business Class (for now), though the First offerings are not perhaps of the quality offered by some Star carriers, they are more consistent and more easily booked.
As a top tier member of all three major alliances, I still put oneworld as my preferred choice be it BA/Qantas internationally and American domestically in the US and Caribbean, though of course I would always opt for Swiss where possible if I can fly on their new planes which are quite simply superb.