i always have 32mm connection, who doesn't want more pressure, and its same price to supply.
The water ring is in 22mm with short 15mm spurs to the taps. Noticeably better when shower(s) are being used and a bog is flushed/washing machine on etc.
Just have a to re-train moron plumbers out of using 15mm for everything as it saves them 50 quid on the whole build.