Anyone know the answer from their single discipline pre-MMA days?
Well Jacare won Multiple Mundials and ADCC championships, Romero a world champ in 1999 and a Silver Medalist in Sydney 2000 , I think Wrestling has the harder competition pool , but on the subject of the question Jacare was closer to being the Pinnacle of his Discipline
Like others have said, getting to the top of wrestling is way harder than getting to the top of BJJ. So it's hard to compare. Jacare spent more time at the top, but Romero was the best wrestler in his weight class when he won the 1999 world championships. I don't know why the UFC always says olympic silver medal and never mentions that he's a world champion. I get that olympics is more high profile, but the competition in the world championships is the same and they should still mention it.
The big difference I would say is that outside of some very rare guys like Karelin the talent pool in wrestling doesn't drop off as quickly behind the top guys as it does with BJJ, just to be at the Olympics for a major nation denotes a very high quality wrestler probably not too far behind guys who win medals.
ADCC and Jacare was best at his weight.An Olympic silver medal is a pretty definitive second best in the world. I don't know which jiu jitsu competition to compare to that.