As far as digital watches go, the most accurate I've seen are the Casio gadgets that get a nightly time-hack from one of the 6 clocks in the world that transmit a synchronization signal. If you're in range of the signal, your watch will have a GPS-quality hack.
Problem is, many bomb-sponge countries in the world are well outside the range of the synchro signal. As soon as you put on your war pants, your watch isn't any better than a $36.14 watch at the BX.
For daily use, however, they can't be beat.