I always have my Omega Speedmaster Professional 3570.50 with me when I fly. It has everything you need in a pilot's watch - a very readable face with white markers and hands on a black dial, and a reliable chronograph. Forget the wiz wheel watches, with the possible exception of the Breitling Navitimer/Cosmonaute (24h version of the Nav).
Here's mine in the Tiger Moth with me in a quiet moment, waiting for landing traffic before taxiing out:
Flying something slightly more modern than the Moth
With a leather strap it can be used with a suit as well
