Help needed - Omega Moonwatch or Sinn U50

Depends on what you're after. The U50 is way more durable, and I would consider it a better "go anywhere, do anything" watch. The U50 is also way cheaper and easier to service. Your local watchmaker should be able to oblige. 

The moonwatch is prettier and more high maintenance when it comes to servicing. It is a comparatively fragile watch. So the question is....
 

Do you want tough, dependable and plain or pretty, fragile and high maintenance? 

Thanks; makes lot of sense. I think I fancy Sinn U50 more somehow; although it looks ’plain’; to my eyes, somehow has a lot of character due to its uniqueness. Somehow those moving syringe style seconds hand on black dial with AR coating looks captivating everytime I look at it :)

Two completely different watches.

With what you have I would probably go with the U50. The Zenith and vintage Sub give a good dynamic that I think the Speedmaster would not add too (I believe the way you'd use a Speedmaster could be interchanged with a vintage sub, and you have a chrono in the Zenith). 

Assuming you wouldn't go in the water with your vintage sub, seems like u50 might be a good choice. Like @Richierich mentioned, the U50 makes the Speedmaster look fragile (even though you could technically go swimming with it). 

Currently have Sapphire 3861 Speedy Used to have 1861 Hesalite 😀

Not here to bash  the commentors but the Hesitate Speedys are still NASA flight certified. What that means is the piece is capable of going from Earth to space without any problems and back again. Mind you during the trip and EVAs the watch was designed to be exposed to swimming ( and activation of the pushers under water, try that with the screw down pushers on Rolex Daytona AKA Cosmo-NOT) during training and recovery in the sea. Even though ONLY rated for 50m water submersion. 

As a piece of flight equipment it's tough as nails.  EVAs go from a "normal" human sustaining pressures/temps to the vacuum of space on the exterior of the spacesuit. Go from sunlight to darkness where the temperature swings are WAY more severe and enduring than our puny human hands can allow.  

During flight it Hesalite may be scratched in all the fun but will most likely buff out with a problem. 

Love the SINNs though....Don't think you'll be disappointed with either. HAVE FUN!!

For me it's the Speedmaster for sure. A much richer piece. Histroy, movement looks... 🎯

The Sinn is tough but with an off the shelf movement and a  flat crystal. Nothing compared to a domed/boxed saphire or hesalite (if that matters to you). Also hard to choose between the black and steel version.

I would wear the Sub over the Sinn any day. Unless I'd really need/want to have a diver for diving and ruggedness sake.

Would the Omega potentially replace the Zenith for you?

While I'm biased and love the Speedy if you couldn't already tell by my forum name, I don't think fragility is something I would use to characterize the tooly Speedy (except with respect to depth rating which the U50 blows the Speedy out of the water). 

As others have pointed out above, I'm not sure any other watch has endured the objective testing the Speedy has (extreme temperature variation, shock, acceleration (to 7Gs), humidity, certified to withstand the vacuum of space, etc. that caused all other watches in contention to fail including the Rolex).  

Not saying anything bad about the U50 (which is great and robust esp with the tegiment hardening option) and if you are looking for a diver for actual diving or Summer water fun, I agree the U50 is clearly the safer bet.  

Some good insight here for you already, but I'll throw in my 2 cents as I've owned both of these watches since each was released. 

First, the Speedmaster has been just as tough as the Sinn in my experience, but I don't do super extreme stuff (as I imagine most of us don't). I play catch with my son, do chores around the house, build LEGO, and bike to work, and wouldn't hesitate to do any in either watch. 

I find that they both wear smaller than their stated dimensions, and I'd say the U50 wears closer to a 5 digit Sub. 

These are two watches with their own distinct style and personality, which is why I like them, and there honestly isn't anything I'd change about either, but they are very different from one another. The Speedmaster will work with almost any outfit in my wardrobe, and I cannot say the same of the U50, which has something of a brutal design language. 

I'd say it really comes down to planned use case, if you need a watch that will be flexible in what you do and where you can go with it, the Speedy is the right ticket. If you want something that's easier to kick around in and dress down a bit, the U50 will offer more presence. 

I agree with @unseenhero in saying that the Speedmaster will be in the same vein as the Zenith and Sub (5513? 12?), as it's got a classic sports watch presence about it. The U50 will definitely stand apart, but I'd also maintain that the Speedmaster, especially with its new tapered bracelet, lean more formal than either. However, I see in your description that you have own watches from the likes of Moser and Patek so perhaps you're already covered in this realm, in which case I'd point you toward the U50. 

Thanks everyone for valuable and detailed inputs; just realized I have so much to learn reading all your views :) @buettner I agree with you, will lean towards U50 given I already got quite a few of those classic sports watches. 

For me, Sinn was just one of those watches that got stuck in my mind and when I finally saw one in flesh (particularly U50 although it wears much smaller than its specs but still good for my wrist; wish it were an inch bigger); I knew I loved it. It will kind of stands out in my collection - speedy would kind of blend in with other watches but Sinn would surely wont get lost in the crowd. Having said that, Speedy is just so cool w that domed, Hesalite crystal. I cant stop myself walking into Omega showrooms to take a look at them like a kid at a candy store (btw, that's the only "modern" Omega I fancy; although I love my vintage Omegas)

Knowing myself, I know I would end up buying both in next few months but first, will get the U50. Aah... my wife is going to be so very pissed at this :P 

Thanks again to all; definitely, learnt so much more today. 

D'oh. Buying both was the obvious solution. 😂

Good luck!

Sinn, hands down, the quality, craftmanship and solidity are not to be beaten.

I've owned a U1 for a long time and love it; and the U50 is even better (smaller in size) with Sinn's latest technolgy and  engineering! Easy choice, but I also own Omegas and love them, but I feel that the Moonwatch to me is too much of a marketing gimmick for me!