First Omega?

Without providing any personal information, can you give us a little more to work with? What kind of job will you be doing? Are you doing some kind of engineering or medical work where you’ll be around powerful magnetic fields? Working a lot with your hands? Or are you joining academia, and perhaps wearing a blazer or suit every day?

As Dan points out, Speedmaster is a whole range of models—but the one most people would think of, and the one that would probably best commemorate a life milestone, is the classic Moonwatch. There are plenty of preowned examples out there that can be picked up for a bit more than the reduced but not wildly more. It’s good that you’re open to preowned watches—that vastly increases your range of options.

That said, the Speedy is a tool-ish “boy” watch (my wife’s phrase). It’s elegant and classy in its own way, but it’s also large, overengineered and rugged with a very busy dial and lots of pushers—it doesn’t project sophistication and understatement to most eyes. If you’re going into academia and are going to be dressing up most days, a nice dress watch might suit the occasion far better.

Omega has plenty of options—the DeVille line, but also (as sort of a compromise between dress and tool) the Aqua Terras. I’d also consider a preowned Rolex Datejust or Oyster Perpetual—probably the gold standards for nice first watch/milestone pieces. And you can get the backs of those engraved if you want. Bit trickier with the Omegas since the casebacks have lots of crap on them already or have display backs.

If it's the aesthetic you like, I recommend a modern 310.30.42.50.01.001 hesalite Speedmaster Moonwatch. You can find them almost new on the secondary market for up to 2k below retail price, and sometimes still under warranty.

Based on your story, my thinking is as follows:

1. Sentimental Value -- You'll be paying more than a Speedmaster Reduced, but for a major milestone life accomplishment you'll be getting a watch recognized as a robust yet highly celebrated timepiece with a storied legacy. Also, for someone with a PhD, you'll have a watch trusted by rocket scientists and astronauts for timing at the frontiers of human endeavor.

2. Mitigate maintenance cost -- All mechanical watches eventually come with unavoidable maintenance costs, and simple rule of thumb is: the more expensive the watch, the more expensive the maintenance. If you buy an older or vintage timepiece with unknown service history, you’re signing up for those costs almost immediately. Go for like-new (better yet, still under warranty) and you shouldn't have to worry about those cost for a while.

3. You haven’t fallen down the collecting rabbit hole [yet] -- We collectors are pedantic hoarders. But still often friendly and knowledgeable. You have to thread the needle with our advice as we are prone to perfectionism and over thinking. If you're just looking for one nice watch that is special and meaningful to you and that you will enjoy the rest of your life, and possibly hand down you your kids, it's okay to spend a little more to make it that special. Get what speaks to YOU and makes you feel excited each morning you put it on. Don't listen to any of us on this last point. There are no objective "specifications" for what will excite you or make you feel good.

You should still do some homework about buying on the secondary market, but a modern watch like the current hesalite Moonwatch should afford you a lot of buying options and opportunity for savings and last you a lifetime. You can go on eBay and Chrono24 to survey the market and get a sense of pricing.

I'd go very simply with buy the current gen Speedy Pro. It will work for years worry-free without needing a service.

New if you like, used for a not insubstantial discount.

Going to a boutique and trying a few on would be a good move.

Maybe you won’t buy new, but this could help you with the choice - seeing the size, the wrist presence, the colour of the dial, the type of lugs, whether you like the classic version or could be open to variations - which the second-hand market has plenty of.

Dreaming of a watch on a screen is not always a guarantee of wrist time, and many here probably agree..!

Smart Casual (Think chinos, shirts and blazer) with occasional full suit days.

Thank you very much! I think the classic current moon watch might be the winner but I’ve got a lot of looking/reading to do 😀)

Maybe a Seamaster 300Mc is something for you. Its durable and doesn’t cost that much in comparrison to a speedy. And you can wear it always. It fits to almost every occasion

I have a 3511.50 in the UK, just back from a service. Though it's not a moonwatch.