Board Thread:Questions and Answers/@comment-24847491-20141024100731/@comment-5398287-20141025152042

If we are to judge based on all of their abilities and only what we've seen from them, and not just Zanpakuto or spiritual power or whatever...

(Note: these rankings and places are only separated by very small gaps in power and skill in the beginning.)


 * 1) Yamamoto - Without a doubt the strongest individual captain, as far as I'm concerned. His Shikai has the power of a Bankai, his Bankai has the power of the sun, and he is a master of all four Shinigami arts, as well as an excellent leader and tactician. It's telling that Yhwach had to end up using a clone to wear him out and steal his Bankai before he could defeat him.
 * 2) Shunsui - Given how he was promoted to Captain-Commander after Yamamoto's death, this is somewhat of an obvious choice, but putting that aside, Shunsui has proven himself a cunning and resourceful combatant. His battle with Starrk stands out in the series as the only battle where both combatants refused to explain their powers and lied by omission to their opponents about them while trying to discern their opponent's abilities, as well as one of two battles where a Shinigami beat an Espada with only their Shikai (the other being Kenpachi vs. Nnoitra). His Shikai is also fairly powerful, which helps.
 * 3) Unohana - 3rd place almost seems too low for her, but I can explain; I'm only judging her power based off her one canonical fight, which was with Kenpachi, where she managed to kill him several times in rapid succession without even trying. Enough said, honestly.
 * 4) Kenpachi - And speaking of Kenpachi, he's in 4th place. Why? Because he's got an absolutely insane amount of raw power, but lacks the skill to really control and refine it, although this has changed to some extent in this final arc. Doesn't change the fact that with this raw power he defeated a released Nnoitra by merely swinging his sword with two hands and manages to blow something up every time he takes off his eyepatch. On top of that, he now has access to his true Shikai, which has proven powerful enough to cut through space and stuff.
 * 5) Urahara - While powerful Reiryoku-wise in his own right, most of Urahara's high place in the ranking comes from his overwhelmingly intelligent and tactical mind. He has proven again and again that he is the smartest character in Bleach, in addition to being a grandmaster of the Shinigami arts alongside Yamamoto and Aizen and having a very versatile Zanpakuto. In my opinion, this would allow him to defeat all ranked above him - and most certainly all ranked below him.
 * 6) Byakuya - By far one of the strongest and most skillful characters in Bleach, Byakuya is fast, pragmatic, and deadly as all hell. His Shikai and Bankai are both incredibly hard to get around, being essentially 1000-1000000000 blades to dodge and deal with all at once, and they've only gotten stronger after his training at the Royal Palace. His sheer Kido mastery is also a big plus.
 * 7) Gin - Despite his relatively mediocre skills in the Shinigami arts aside from swordsmanship, Gin gets 7th place because of his sheer trollery and manipulation in combat, as well as being the only Shinigami savvy enough to lie about what his Bankai can do. With all of this in conjunction, he came this close to killing Aizen, who outright admitted that he would have died if not for the Hogyoku coming in.
 * 8) Aizen - 8th place may seem like a rather low place for such a character, but I have a good reason. Putting aside his Hogyoku transformations, Aizen is skilled in all four of the Shinigami arts, and certainly has the power to take on most characters in combat. However, most of his victories over other characters have stemmed from the use of his Complete Hypnosis, which is powerful to the point of being OP. Standing on his own merits and fighting without his Zanpakuto, Aizen, in my opinion, is not quite as powerful as the above combatants, if only because we've seen him do very little of that prior to the Hogyoku transforming him.
 * 9) Hitsugaya - He's got the strongest ice-type Zanpakuto in all of Soul Society, he's quite the tactician, and he's got skill in the other arts to back it up, as well as quite a lot of spiritual power and the ability to use his Zanpakuto in creative ways. However, what puts him so far down on the list for me is his relative immaturity and tendency to let his emotions rule him at times: a prime example of this would be in FKT, where Aizen got him to leave the entirety of the remaining forces vulnerable by tricking him into stabbing Hinamori. Dat rage scream.
 * 10) Mayuri - While not as intelligent as Urahara, Mayuri is still a formidable opponent in combat because of his nature as a scientist and his willingness to experiment on himself. In addition to his Shikai and Bankai having powerful poison capabilities, Mayuri's most recent battle against Giselle and her zombies has proven that he can create counters to pretty much all abilities with limited information and take on far more powerful opponents with his own inventions and cunning.

That's my top 10 because I'm feeling too lazy to assign the rest of the captains a ranking right now.