A healthy Zion is amazing. BUT... he still walks like a weeble wobble and seems to be a bit of an injury risk. But if he stays healthy, he has HoF type potential - he has good awareness on both sides of the court.
If Obi-1 is Amare Stoudemire (2002 #9 overall pick) all over again, that's a potential HoF too. Amare didn't develop a post game or outside game until late in his career - after a few knee "tune ups". Obi-1 is a bit more advanced in that regard. He has a few effective post moves, can spin a bit and already has a serviceable perimeter shot. Plus he's already more than twice the passer Amare ever was.
Obi-1 like Amare doesn't have great defensive awareness, but with his length and athleticism is good for a highlight block every game (generally of the impressive, but useless sort that goes out of bounds).
Another analogy - the college Kenyon Martin was very impressive. He was (listed as) 6'10", pure power, totally dominant, larger than life. In the NBA, he shrunk to 6'8" (ha!) and didn't have the physical advantages as expected... and while he had his moments, he was merely a very good borderline all-star at his best.
But yeah. We haven't seen him on the court yet against pros, so we don't know. Some guys just have it, some don't. Another off the wall analogy (totally different players, I know) Carlos Boozer was another player from the 2002 draft - he feel like a rock in the draft (2nd round pick, #35)... but made a few all-star teams and could have done more if not for frequent injuries. (incidentally, they're #1 and #2 in WS's for that fabled class that included Yao Ming as the 1st pick)
But hey, years later Shelden Williams was another Duke product, similar size, skills (in college) to Boozer, but was a bust for a 1st round #5 pick overall. Sometimes players pass the eye test in college but can't find themselves in the NBA.