For me, this question raises some more questions and makes me wonder if you're actually asking the right question.

How are you measuring the 'solid' and 'future-proof' qualities? How will you know, objectively, which approach provides the 'most' of each?

My understanding of hexagonal, clean and onion architectures is that they all have similar themes and principles. Have you identified clear differentiators between each, so that you can confidently identify which is which?