I love my Nomos Tangente (my only German watch) and the Bauhaus inspired watches in general. From the German brands (excluding high-end brands like GO and ALS) I'm quite fond of Sinn and Stowa and would love to own some Sinn U50 (and maybe 104 and 556) and a Stowa Flieger down the road. Overall I think German brands strike a good balance between unique design, price, quality and heritage. I don't mind that most of them use stock ETA and Sellita calibers, as this makes the maintenance easier and cheaper. Nomos's in-house calibers are great, but given that many automatic models have prices in the 3-4k EUR range I'd probably go with something else at such price points.
My main issue with German brands is that it's very hard to try them in person, as they don't have strong distribution channels outside Germany.
I’ve read multiple experiences about defective Rangers - as far as you know, is this a widespread issue or isolated incidents?
From what I've gathered the incidents are not Ranger-specific, but rather some general issues with the manufacture calibers. I'm guessing that overall the defective movements are a small fraction of the total movements produced, but I can't speak to any particular numbers.
The general consensus seems to be the Ranger wears better, but the Omega is higher quality and more interesting.
I guess that's a nice summary, although the quality gap is small and the "more interesting" is quite subjective. The Ranger has a better bracelet for sure - it was one of the things that got me interested in the watch in the first place (Tudor got on my radar for the BB58, but I didn't like it's bracelet).
I have a Ranger and I've tried the 40mm Railmaster and my opinion is that the Ranger is a better value for the money. (although the difference is not huge - something like 3k EUR vs 4k EUR) Yeah, the RM has a better movement, but other than this and the Omega brand equity I don't see it having any major advantages. Both dials are fairly spartan IMO, but this is something, I actually like. I really dislike the fauxtina used by the RM to make it look older, though - I've never been a fan of faking a vintage appearance. That looks OK on the white dial, but it's pretty obtrusive on the black dial IMO. If I ever get a Railmaster I'd probably go for the version with the denim dial and the white lume markers, because of this.
I know the Ranger is widely hated for its "boring" dial, but I totally love it. That's the one watch I wear almost all the time these days. A very understated and comfortable timepiece. Mine runs fairly accurate - it has lost something like 15 seconds in the past 2 weeks. Despite a bad initial experience (the first Ranger I got was defective and had to replace it), I totally my Ranger and it keeps growing on me every day. But again - I wouldn't mind getting an Omega alongside the Ranger down the road, although I find the AT and the Globemaster a lot more appealing than the Railmaster. Again that's just because I really hate artificial aging, and for all that has been said about the Ranger it doesn't actually use fauxtina. (the lume markers are some light shade of green)
In terms of dimensions/comfort I'd say they are essentially the same. Both fit perfectly my 6.7 inch (17 cm) wrist.
WR: 100m (but no screw-down crown) = You're good to go. Not swimming, obviously, but everyday type stuff. You might even consider showering with it on (quickly) if you're not too attached to it.
For the record - I was swimming for 15 years (mostly in sea water) with a watch rated 100m without a screw-down crown and it did fine by me. (at some point it started to get some moisture, which became visible as fog on the inner of the crystal, and I had to replace the gaskets, but that's it) I think pretty much every well-made watch rated for 100m should be perfectly fine for showering/swimming/whatever.
They normally don't lume the numbers - just the markers near them. (see https://teddybaldassarre.com/blogs/watches/dirty-dozen-watches)