Pre-timeskip Smoker at the very best - and that's being very, very generous.
You guys are MASSIVELY overrating both of them.
Even Smoker, who was way stronger than both of them and had a significant growth himself (learning CoA and CoA, being promoted to VA etc.) is clearly not in the league of the top or even higher tier fighters right now.
Now we're talking about two dudes, who are still two steps behind even VA level, which Oda basically confirmed, once he corrected Coby's text box in the actual volume (still only a captain and not even a rear admiral).
Anyone thinking that those dudes, who were complete and utter fodder pre-skip (one-shot material to even base pre-skip Luffy) are now suddenly tobi-roppo material - fighters that even current Sanji etc. have to fight serious against - has lost their mind.
Very tricky to suggest for the amount of info we hold at disposal.... but in my mind I think Coby is still captain mostly for his actions at MF rather than his actual level of power and Marine competence.
So that being said and also considering how one day he will likely become admiral (but so will Smoker probably) I can still see him in the low range elite yonko commanders level in one of the worst case scenarios. We also have another element, his will to capture Boa who is probably an elite yonko commander level herself. I don't think he is necessarily that powerful but perhaps.
He kept training with Garp and Bogard most likely and that is promising. He was terribly weaker than Luffy and likely still is, but how much is the question. I think the ratio gap probably lowered.
Dude, you are really smoking crack ...