I believe, and historically seen also, Patek, Rolex, and Omega are your best chance. But they're not within the 2K budget.

Pocket watches can be restored to run but won't be used for daily wear. The criteria are different and way less than modern wristwatches. And don't get me wrong, every part can be re-made, but it'll be too costly to do so once they're not mass-produced anymore. The machines to produce them may be worn out, and it's out of the question to repair such a machine only to produce one or a few parts.

Solar Beat?

Please define 'Best'...

Browse catalogs or Armbanduhrenkatalog from 1993 and see that for many many watches from that age you unfortunately won't be able to find parts anymore.

Your request for "that will last me half a century" will make it extremely difficult. Within 50 years, you'll sure need to exchange some (wear) parts, like crown, gaskets, and probably glass. Which brand will guarantee you that you'll be able to obtain those parts in 20, 30, 40 years from now?

To be only a bit sure, I'd skip all micro brands, and brands that were born in the last 10 years. But even the established brands might not be able to sell these parts for over 30 years.

The answer is always Rolex..

That's probably when your main objective is to read the time on a wristwatch. For me, that's a secondary function, I love the technics behind it. And therefore love the Devon very much as well.