jinbei fought who's who bounty of ~ 500 mil
sanji fighs queen bounty of 1.33 bil
zoro fights king bounty of 1.39 bil
luffy fights kaido bounty of 4.6 bil
looks to me like n2 and n3 fight people on similar threat levels looking at 4 of them on this list while n1 and n4 are distinct but you can tell yourself what you want.
hopefully we'll still be here when the matchups against bb pirates are in and zoro and sanji opponents have bounties of a 100 mil within another .