I have two pairs of the Assos Mille GT bib shorts, which are their cheapest model. (Still not cheap). Super comfortable however, so I also have some bibtights and 3/4 from them, none of these are the highest spec ones. Above the GT in the ‘comfort’ series (comfort = MIlle, their racy compressive ones are called Equipe) are the Mille GTO and if I ever win the lottery I’ll take a good look at them.
My bibs are a few years old though and I’ve just seen a model they call Mille GTS spring/fall, which are thicker for more warmth. Given we don’t really have a reliable summer here in the UK I’d be very interested to know what people think of them, especially the temperature range that they work in.
Other brands I’ve tried are Endura and Santini. Not tried any others. TBH the Assos basic Mille GT are very good, even last year’s, but watch out for models with pink pads, the more recent pads are black and IMO black is a better colour 