My view is that people like Roger, Rocks, Garp, WB were on a league of their own. You have Kaido et being their replacements this generations.
Tier 1 (in their prime): the best of the best.
- Roger - easily the strongest person along with Rocks and Garp during their time. It took him and Garp to defeat the most dangerous crew at the time and the man only knew one true rival in Rocks. WB was more of a friendly rival it seems.
- Rocks - absolute madman and powerhouse it seems. His crew was stacked and it took both Garp and Roger to put him down. Must have been a beast.
- Garp - same as Roger. Hero of his respective faction and has the power and feats to back that up.
- Whitebeard - friendly rival to Roger and able to clash with him for a number of days without neither dying. He belongs in this special tier.
- Sengoku - seems to have been on par with Garp or at least implied as such by Roger.
Tier 1.5: these are guys we know nothing about but seemingly are at least on par if not stronger than yonko. could also be as strong as the PK level characters. All we know is that they are likely above admiral level.
- Im - not sure if i'm over-hyping but I see Im as the strongest in the marines. Not only do they seem to have been around for a long time - given the artifacts - they seem to have absolute rule over the marines. The CDs have control over the marines but rarely do we see them interact with the gorosei.
- Kong - nothing is known about how powerful he is, at the very least we know he is as strong as prime Garp or WB as he was part of that era and an admiral at that. Could just as well have him in the same power level as Akainu etc.
- Gorosei - these guys should at least be stronger than your regular admiral but not too strong as to be too far off the yonko. The .5 emphasises a bridge in power levels. For example a member of the Gorosei could extreme diff a yonko but could also lose to one all in the same.
- Dragon - the most dangerous man in the world and one whose powers we know absolutely nothing of. I don't think he is as powerful as prime Roger, WB et al (he could be but who knows) but I believe he should be stronger than an admiral given his subordinates performances.
Tier 2: This is basing them off their bounty to avoid having to overthink. I personally think BB and Shanks having some sort of weird advantage and that Kaido and BM only have higher bounties due to being more destructive.
- Kaido
- BM
- Shanks
- Blackbeard
Tier 2.5 (in their prime):
- Rayleigh - well we know Rayleigh was one of the strongest people in his time and he was and still is an absolute beast this much after his prime (stronger if not on par with an admiral), one can only imagine how much of an actual beast he was. The Dark King.
- Oden - naivety aside, this guy was a rampant monster who only had Yonko contender characters above him. Losing to Kaido and being swatted by WB and Roger. Everyone else seemed fair game though and respected his strength. Think he was 3rd or 4th strongest in the Roger ship.
- Shiki - rival to WB and Roger, to what extent and how powerful? Who knows. Seems like what would have happened if Buggy was actually serious about getting stronger.
Tier 4:
- Akainu - I put him first because I feel as though he is the strongest admiral. Given his current position and his win over Aokiji.
- Aokiji - self explanatory as to why I put him second.
- Kizaru - some people seem to think Kizaru is the strongest admiral, I just think he is meh compared to Aokiji and Akainu, only thing is that I place the O.G admirals above the new guys.
- Fujitora - basing this off the fact that he has been deployed twice to go after some decently powerful individuals but that could also indicate that Akainu sees him as expendable. Still, we know more about him than Greebull.
- Greenbull - he is an admiral so... lists?
- Marco - there is an ongoing discussion right now about his efforts in Marineford but given how he is viewed in the world, is still standing and protecting the last bit of WBs territory, I put him above your average yonko commander.
Tier 4.5:
- Mihawk - easily the strongest person after the Rogers, Dragons, yonko and admirals of this world.
- Gaban - same as Rayleigh but not confident enough to have him above admirals.
- Ben Beckman - seems to be the most recognized and feared out of the RHP.
- Sabo - I think he is as strong as an admiral given how he and Fujitora fought without either one really come off worse off or truly threatening the other. The revolutionary army commanders as a whole seem a bit difficult to place so will place him slightly below them.
- Luffy - Luffy is a special case. He is clearly stronger than YC1 but also weaker than an admiral or yonko. This is where I place him currently, might see him jump to the same categorization as an admiral by the end of the arc.
5. YC1:
- Lucky Roo
- Katakuri
- King
- Yassop
- Shiryu
6. YC2:
- Smoothie
- Queen
- Jinbei
- (someone from BBs crew) x2
- Denjiro
- Kidd
7. YC3:
- Zoro
- Jack
- Neko and Ina
- Law
- Cracker
- Snack
- Sanji
Il update this list as I go along. Got so bored just thinking about anyone that isn't YC3 or above. The YC sections are pretty straight forward I think.