I’m swapped out the cheap leather strap on this quartz Seiko chronograph watch and replaced it with a nato strap. I’ve been really happy with the results. I’d be curious to hear which watches people have transformed by changing the original strap.
FWIW, this is a Seiko Chronograph SNN241, which I got for a round $80 on Amazon a few years ago.
I’d say anything steel, but on the dressy end of the spectrum, and particularly anything that comes on an alligator strap, is usually the most dramatically and successfully “transformed” by a strap change. Many steel “dress” watches can readily become “sport” watches if paired with a steel bracelet.