If I could have only one pair of cuff links, they would be similar to the vintage double sided 14 karat gold pair in the photo.
I generally prefer linked cuffs when I am wearing a suit, and, as a class, discreetly sized gold links have considerable advantages over the alternatives. They do not tarnish, they look good with suits and shirts of any color, and, when purchased without a retail markup as most things vintage can be, they should always hold enough value to be exchanged for a meal if worst ever came to worst.
Discretion is paramount of course if a man is looking for one pair and one pair only. Conspicuous sizes and those with gems, enamel or noteworthy designs do not work as an only pair. Small geometric shapes with or without a little etching are best.
It is easy to spend more but the careful shopper may find vintage choices for less than $300. eBay is a good place to look.