The world's your oyster at this price I guess.
A Blancpain Fifty Fathoms is a little above this budget but worth striving for.
Rolex GMT2c is a nice work watch
Any of the Jaeger Le Coultre range may appeal, specifically the Master Compressor Range
IWC Ingenieur
Have a look here for ideas http://www.blowers-jewellers.co.uk/ they have pre-owned high end stuff, obviously will be cheaper privately
There is a very nice Blancpain Flyback on the sales corner at the moment - I know you can't see it but pic below for £3,850