They also, crucially, have sizing beyond just S/M/L et c. but within each they have regular (fat) slim (kinda fat—this is me) and tall. I think I've even seen tall-slim and maybe one other size on there (do they have a Trim size for people who are actually skinny, or is that another brand I'm thinking of?)

That's a must for getting a decent fit for off-the-rack clothes. Even t-shirts.

Plus, they don't even put logos on their polos, which is the one place that actually-nice clothes can get away with a logo. They're not the best-constructed, but they're not terrible, and no logo. BB's polos are better-made and use nicer material but when I wear them I feel like a douche because of the stupid embroidered sheep logo. I think both favor tennis-tail though, which sucks if you like to wear them untucked.