The gauntlet has been thrown, and the challenge accepted. Omega didn't catch up to anywhere near Longines in the quality of their movements until the 50's at the earliest. Rolex wasn't playing on the same level until the 60's, and that's debatable. Longines' 30 series was as good as any of the 30 mm Omegas produced, and they had several other excellent smaller sized calibers like the 23Z and 12.68 manual winds. And as good as Omega's 55x/56x series was, the 290 series was a better engineered movement with a more efficient and durable winding system plus a larger balance wheel making it capable of more consistent timekeeping. IMO, it wasn't until the 60's that Omega played in the same league.
Longines was also a pioneer in the 36K bph field, sending the caliber 360 to the chronometer competitions as early as 1959. GP beat them to market in late '65 or early '66, but Longines' 43x series was recognized as the best high beat movement of the late 60's. They were guaranteed to keep time within 30 seconds a month - way better than chronometer standards of the time.
This will make you chuckle. Here's my Ultra-Chron 431 with it's 30m water resistance test slip. Not bad for a 40+ year old 18ct watch.
If some cruel act of fate forced me to decide between my '66 Constellation and '60 Conquest, there'd be listing for the pie pan the next morning. Take a look - can you blame me?
Also, we all know how cool the casebacks are on the Seamasters and Constellation. Medallions rule, right? Well check out these.
(photo by JimH)
The front of a Flagship ain't too shabby either.
For the last example, the watch that several watchmakers I know (Jesse too) call the best looking vintage dial design they've ever seen:
I could show you more, and stainless steel is poorly represented here..... because I only own one in that metal currently. It's my '73 Admiral C-case with the blue dial. My favorite day off vintage watch. However, the best stainless steel Longines you could own would be either the Conquest Power Reserve caliber 294 or the Legend Diver caliber 290. Both will set you back a tidy sum, but both have appreciated steadily and it's a safe bet they will continue to do so.