It's always interesting to see the disparity in sizing between different brands/lasts even between two people with same size feet.
I am usually a 10D but technically a 9.5 E in US (which is also my UK size mostly).
Edward Green in most lasts (606, 82, 888, RLPL) 9/9.5 E or 9.5/10D
Either works well for me.
John Lobb 8000 in monkstrap chapel, 9E
But 8000 in most laceup bals, 9.5E
JL 1105 I am a 9.5E
Sandon last (8200?) 9.5E
Allen Edmonds all 10D. Some I have to go to 10.5 D.
Alden barrie last 9E
Santoni mostly 9.5
Vass U last 43.5. 44 can work on wholecut/closed laced U last styles.