I never thought I would find myself replying to a watch thread!
But for me, the most important feature is the ability to switch between local time and GMT, and have these both shown in the 24hr style. If you're flying in the UK then fine; if you are flying somewhere where the time difference is, say 5 hours, or worse, 4 1/2, it really helps to be able to switch over to GMT as you get in the cockpit, and back as you head for the crew bus. I believe some watches even have several time zones....mine doesn't but it would be handy.
This usually means buying digital, and $100 is plenty unless you fancy getting mugged on your stopovers!