Im a big watch geek.
Dress watches are smaller in general, 36mm is classic, some classic dress watches were a little smaller, but most guys will shy away from anything under 38. I would not go bigger than 40 but honestlu for a true dess watch, >39 feel like its too big.
Quartz will save you over manual or automatic. Give you more options for designs.
Honestly i am a vintage watch lover so i really think you wlll find quality and value with used and there are good little servicable [read not throw away] finds for about 100
Highest quality and good price will be something like Seiko, Orient, Citizen, maybe pulsar...read japanese,
Stay away from fashion house watches, let.them make jeans, buy a watch from a watch company
Orient, you can find a nice automatic like a Orient Bambino a clean used one since new long island watch had them about 149, will probably be biggest value in dress auto space, looks more expensive than it is. U can get lucky and find someone unloading a used bambino under 100 sometimes
But good reliable solid quartz, Orient Capital'
99 bucks, attractive classic design
https://www.longislandwatch.com/Orient_UG1R009W_Dress_Watch_p/ug1r009w.htm?gclid=CJDEsN6GhdUCFZiEswodSg0F6gBtw seiko owns orient so quality is there but the allow them to be a distinct watch house

40.5mm so its sy limit if what i would do dress wise but for a modern watch it works, most guys will want 40 to 42 so its in the sweet spot