Sonos play isn’t really a portable bluetooth speaker as you say; it’s easy, but you could just get a bluetooth adapter for your normal proper hi-fi and enjoy sound that isn’t limited by being that sized.
I own a soundlink mini and I have a friend with the cambridge audio version (the smaller US triangular one) I’d wager that there’s probably not enough in it to justify the price difference.
I think the soundlink mini is still the gold standard, but not by a huge amount. It is, however, a very nice THING. In the way that your scott carbon frame will probably be better than a lynskey titanium frame. But you still want the ti frame.
Also, if portability is the prime factor, the bose wins – it’s small enough for you to think “sure, I’ll put that in my carryon for this flight”, whereas pretty much everything else wouldn’t come with you.