Both the Hamilton and the Casio keep better time than the Omega. Not by much, mind you, but they do. The Omega is a Swiss Automatic Movement and it is a beautiful watch, but in terms of accuracy, my $200 Casio is better.
Sounds like it needs to be adjusted.. How old is the Omega, and is the error consistent (ie: either short or long on time)? The real problem is finding someone who can adjust it, meaning really knows as opposed to saying they know.. Which SeaMaster by they way.
Interesting thing about the Hamilton Watch Company.. it is now owned by a Swiss company. Hamilton Watch Company also manufactured Railroad watches ‘back in the day’.