I think it depends on the last. I find AS to fit as well as C&J in the same size (albeit AS' F is C&J E), and comparable to EG and G&G with the latter two a half size larger.
I find brands like Cheaney, Barker (Black), and Tricker's to fit quite generously.
Subjectively, I find the 724 last to be roomier. If you consider the 99 last of AS, I'd recommend a half size larger.