1960s Seamasters?

And certainly any hand-winding Seamaster, e.g. with cal 420 or 601, would be reliable IMO.

IMO the 550 family is the best there is.

550 is the base 17 jewel automatic movement ,552 is the 24 jewel, and the 551 is a 24 jewel chronometer qualified(that is, more accurate, not a stop watch) version.

With a date, 560, 562, and 561 are the equivalents of those respectively but that series doesn't have quickset date. So I'd suggest 563, 565, or 564 (17, 24, 24-chronometer).

For daydate I'd love a 751, with 750, 752, an 751 being the 17/24/24-chronometer versions.

The 600/601/602 (3 hander: 602 being a chronometer) and 610, 611, 613 (613 is quickset date, other two just date) are also fantastic movements, manual wind very much like the 550.

The 1000 series is cheaper made, but tend to be pretty good work-horses as well. I really liked the 1012 I worked on (date, 23 jewel, chronometer), with the 1010 being the 17 jewel, and the 1011 being the 23 jewel chronometer.

The day/date versions are 1020(17 jewel) 1022(23), 2021(chronometer), and 1030/1035 being manual winds.

So those are all my favorite pre-coaxial 3 hander/3 hander + date movements.

I'd be curious to know which 1960s movements the OP thinks are problematic. In many ways, that was the peak of Omega's mechanical prowess, with top-notch movements being used even in entry level watches.

I'm kinda the same. Some of the bumper movements have questionable design decisions, but those are earlier. The 'lowest' quality Omega movements are the 1000 series, but they are absolutely fantastic movements, if cheaper made.

Omegas are the ones I ALWAYS find as non-runners/in 'bad' shape, that a quick clean-only service and run good as new! Vs the Seikos/others Ive worked on which show up in 'better' run condition, but are worse off after service.

IMO that speaks to the longevity/reliability. The 60s Omegas stop because the oils/greases turn to glue well before the parts themselves have problems. The other manufacturers I've worked on have damage to the movement before the oils/greases go bad.

REO Speedwagon had a song about this... "Heard it from a friend who, heard it from a friend who, heard it from a friend who..."

IF you buy the cheapest 60s Omega watch you can find, it has likely not been serviced or cared for in 40+ years (despite 5-7 year service intervals!), so I can definitely see folks having trouble with them. BUT because what I said above (they usually just need some TLC and are good as new!), the 'cheap' ones are usually still pretty expensive, so I imagine that a number of watch forum folks are buying cheap ones, finding they don't run as well as an equally priced brand new Seiko (again, on account of them having oils older than the purchaser!), and complaining.