Everything is personal preference.
But for me one crucial parameter is the total length from one lug tip to the other. Or from one center link to the other, if the center links of the metal bracelet are a little longer than the lugs. It is not really the diameter itself.
The total length from lug to lug or center link to center link, whatever it's longer, should be smaller (or at least not larger) than the overall width of your wrist. E. g. if the width of your wrist is 6 cm and the total length is smaller, it looks totally fine. If the total length is the same or even bigger then the the width of your wrist, it looks odd. At least to me.
And bear in mind, a metal bracelet always optically extends the case, and make it appear larger overall. Whereas on a strap, shall it be leather, nato or canvas, the same watch looks more compact.
On my point of view, if the watch wears to large, it cheapens the watch. Whereas the other way round, as someone already said, a 34 mm Vintage Omega on a 7 foot Bodybuilder looks the same odd.
So what is important?
1. lug to lug length
2. width of your wrist
3. and maybe also the shape of your wrist, is it more flat or round on the top where the watch sits.
Easiest way is to try it out and put yourself infront of a big mirror and see how cool it looks, or not.
This is my 6.75 inch wrist. Guess what the size of the watch is.
diameter 36 mm
lug-to-lug 44 mm
Center link to Center link 47.5 mm