Royal oak purchase . Need advice

[Dr H A]

Dear members
I want to ask advice please

I have had great success in building nice collection over past 5 years with All out Rolex
Mostly all are 40 mm watches except Skydweller blue dial that is 42 mm

My wrist size is ~ 7 inches , I am 5 ‘ 11” and weight around 175 pounds

I Do not have a local AP boutique so have to go grey
Cannot decide on size of the watch
Initially I thought 15510 ST blue dial ( 41 mm ) but I am not sure should I consider 37 mm ice blue dial/ blue ??? As I hear AP royal oak wears bigger

Please advise !!