Not a "way to choose shorts", but I've tried a whole range over the past 20-30 years. The ones I currently use are consistently good quality--well made, good fit, and comfortable. They're made by Ground Effect in New Zealand. Here's a link to the shorts they sell:
https://www.groundeffect.co.nz/collections/mens-lycra-shortsThe ones I have are the "Sputnik", the least expensive on offer. I don't need a new pair, but I might go up a grade to the "Supersonics". Main reasons I bought the
Sputniks were that (i) everything I've bought from GE (mostly jerseys) was first-rate quality and fit, and very good value; but (ii) I didn't want to pay more than $100 for a pair of shorts online and hence sight unseen.
I also have a pair of liner shorts which I wear under cycling knickers for shorter journeys (say, a couple of hours). The liners are excellent, and on hot days I sometimes wear them as is.
No guarantees, I know, but I thought I'd mention my satisfaction with ground Effect's products. I have no material interest in the firm, BTRW.
Good luck!