In this scenario where we are at the window at the horse track placing our bets, I agree with Lou_fine's argument. But if you tell me I'm outliving all you guys in my mostly 50+ collector cohort by a freakishly long time, I get unsure. This is really a commentary on my part about the uncertain future of the hobby based on the expensive niche status of new comics today. (Not a thread jack, hear me out.)
To Lou's point, sophisticated collectors are made, not born. I can look back at myself as a little kid in the early 70's and see the machinery that made these books (and so many others, like all of you, I'm sure) aspirational for me. For us, it goes beyond the first hero appearances.
But barring a scenario where young dealers and others foster that mindset, I'd have to fall back on Suspense #3 as the one of the pair more likely to land in the "classic American pop culture" camp and hold value even if comics become a quaint memory in the past. This book, like a Cap 46, has a crossover appeal that a museum curator could appreciate. I would worry that absent a pipeline for sophisticated collectors into the future, a Fantastic #3 has the greater chance of being too esoteric. Heck, a book like AA16 could easily suffer that fate under this scenario. But it is a specific scenario, and not a guarantee, of course. Just my 2-cent view of the long term, and I'd like to be wrong about my underlying theory, but that probably starts with a change in the new comics marketplace.