Modern RAM recommendation for Windows 11

I’ve been asked to spec a couple of family member PCs recently (driven by Windows 10 expiry) and while I can choose the CPU OK, I’d like to ask for opinions about the amount of RAM for a general productivity laptop or desktop PC running Windows 11 to be future-proof for the next 5 years or so.

On my own PCs, I’d just stuff it with as much RAM as would fit, but these are normal budget-conscious buyers, though they will pay what it costs to ensure they have enough.

The way I see it, the choices are really only 16GB or 32GB, but I am open to alternative opinions there. Is 16GB enough?

Thanks in advance.