It’s rare I would disagree with KirbyJack, but I think TTA from #60 onwards was really solid. I’d consider the Human Torch stories in Strange Tales not so great; unfortunately a lot of the Giant Man stories in TTA had the same sort of goofy, half-baked scripting. Once the Sub-Mariner began in #70, the whole book was off and running. Both the Subby and Hulk stories have the classic 60s Marvel-type storytelling charm that drew me into comics in the first place.
Why are they worth not so much? They’re not Spider-Man. Outside of the early biggies, there aren’t any key issues that tie into the MCU or current storylines. And run collectors are a dying breed.