Both are very smart.

But Jeff was responsible for a lot more of what is actually used today than Demis.

Demis is responsible for a lot more of the hype though ;)

I think saying Jeff's contributions were a long time ago must represent some kind of lack of understanding of Jeff's recent contributions.

Jeff has still been focused more on infrastructure, and that is just more hidden most of the time.

I would say,if i was forced to pick someone whose vision to follow, it would definitely be Jeff and not Demis, even today.