This is a good primer.
For me, I got into watches from the history of timekeeping and the mutual role it played in astronomy and navigation. From the standpoint of history, just about any mechanical watch would serve to commemorate this history on my wrist.
A good first mechanical watch might be an Orient for $100.
From there, it's a matter of taste, materials, workmanship, polishing, features (like water/magnetic/shock resistance), heritage, maybe movements and complications. There are also different watches for different occasions and purposes. Different people like different things.
Watches are essentially obsolete except in some rare use cases. I look at my phone when I need to be somewhere on time.
I have found that outside of watch enthusiasts with their enthusiast hats on, nobody but me cares what I wear on my wrist. So it's entirely up to you and what you care about and are willing to spend money on. You don't need to spend thousands to appreciate mechanical watches and people who do usually have some particular interest that compels them to spend that much along with sufficient means not to miss the money.