Suit Supply if you want to look cool, BB if you want to get a lot of wear out of it. SS is more on trend style wise but BB has a long tradition of suitmaking and an older clientele who knows what to look for and won’t be fooled. But if you only need to wear it a few times a year (maybe two weddings and a couple job interviews or something like that) SS is fine and it’s ok to want to look more on trend.
Milano is not a line, but a cut. Milano is essentially slim fit for brooks brothers, and is their take on the Italian fashion suit.
Suit supply main line is somewhere around the quality of brooks brothers 1818, maybe a bit lower since brooks has better construction, but then, regular priced brooks brothers 1818 is a lot more than suitsupply usually
That’ being said, suit supply does not do separates. So if you’re like me and are a weird size you’ll be SOL getting a decently priced suit there. I’m a 46 short jacket and a 32 waist — their paired pant for a 46 is like…40. Big enough they wouldn’t even tailor it down. I had to go custom, which was not worth the price tag.