I’d personally avoid that space unless you’re looking to get yourself into the Rolex Daytona’s or the like, that too to hold for a few years (not cheap).
That aside, Rolex is king in this space whether that’s modern or vintage. There’s also a large following of particular Heuer models (before the merger with TAG). Prices have risen very sharply over the last couple of decades, with momentum in certain pieces (Heuer) stabilising somewhat more recently. Other attractive brands could be vintage Tudor since that brand has made an impressive comeback. Regarding Rolex there’s a vast range from vintage submariners to relatively modern pieces (the ‘Hulk’, ‘Kermit’, ‘Pepsi GMT’…). It’s no wonder that Rolex being the most reputable brand in the world (for 3 years running) retains the greatest value after purchase.
Speaking of Rolex, they play a very smart yet frustrating game with supply and demand. When releasing certain pieces they will constrain the supply so far below the demand that they generate 2 years waiting lists. What that does is push up the prices on them immediately after release in the resale market, sometimes as much as 50-100% above RRP. Just take a look at current going prices for the new highly anticipated Rolex GMT Pepsi. Now of course you might say “hang on, i’ll secure myself one of these ahead of release next time”. Well good luck with that. Believe it or not there are theoretical waiting lists out there for watches that might exist in the future. Yes, you read that right. It’s pretty crazy. And of course dealers will always prioritise their historically loyal customers.
With the vintage space there’s also the whole other ballgame of sifting the crap out to find the gems. Franken watches and unoriginal assembled watches (i.e. parts from different models put together into one piece) are plentiful. You really need to be on the ball. In terms of servicing watches, prices can certainly vary depending on movement complexity but i don’t think having a pure investment piece sit in a safe for years on end would harm it. I guess it can just be taken out and serviced before sale. Or of course you can wind it up and have it run every now and then to keep it running. The only issue with keeping the watch dormant it seems would be faster drying up of the oils. It can always be re-oiled.
Again for me personally I just love the pure enjoyment of these things. Investing in them as a watch lover would curtail much of your enjoyment, to the point perhaps where you don’t wear them for fear of damage.