So all Bane trolling aside, if we want to judge Bane's power we have a few data points to work with.
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[*]He's supposed to be one of the weaker members of the Banite sith. The entire purpose of the Rule of Two is for the Sith to grow stronger with each generation - and yes, some of this progress may be encoded in non-martial areas, but it's clear from the descriptions of Darth Sidious being the "culmination" of the Rule of 2 in conjunction with lionizing his power, and Bane's own interest in the apprentice facing down the master in a one vs. one, that personal power is also supposed to trend upwards. It probably isn't a perfect trend, but over 1000 years that's probably where it goes. So, Bane is likely far, far weaker than Palpatine (it would be pretty unimpressive for the power creep in 1000 years to be minimal). Whether this puts him below Dooku, Vader or Maul depends on whether you think they count as "true" inheritors of the Rule.
[*]He knocks down the foundations of a pretty huge temple. Granted, he charges his attack and had a nexus to work with, but for the latter we do know that Bane is faster in RoT than he ever had been, and faster in DoE than he is in RoT. If his strength in the Force scales the same way, he's likely surpassed his nexus-amped self. This is a little difficult of a feat to judge though, partially because he charged his wave and partially because I get a feeling that he had an aldrenaline fueled rage moment, given that he fails to replicate this any other time in the trilogy.
[*]He struggles pretty mightily against random shadow assassins who can resist his TK (and yet were stated in PoD to be no match for Jedi), mercenaries, etc. Granted, even Luke has notoriously had bad showings, but for Bane, these seem to be the norm, with a few peaks every once in a while.
[*]His growth curve is very impressive, going from having no experience with the Force (beyond using it subconsciously as a soldier and inadvertently killing his father) to defeating the blademaster in the course of a few months.
[*]He is apparently beyond Annedu to the point where he can dominate his holocron (which according to Legacy has his spirit stored away in it).
[*]Even with orbalisks and a nexus, he struggles against Ratska Lsu.
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Taken in together, I'd say that he has to be substantially below Plagueis or Tenebrous for the Rule of Two to make any sense. I'd wager a guess and say that he's below Vader as well, as Vader isn't astronomically below the Emperor. His temple busting feat probably puts him above, say, Ventress as a Force wielder, but I don't think he consistently demonstrates the feats to place him on par with RotS Anakin. As a duelist, his prodigious growth might put him above Obi Wan in his prime, but again, still likely below Anakin. The PT Jedi are far, far beyond the Brotherhood, so him struggling against Ratska makes me wary of this.
So in the Force, he would probably lose to mid-CW Anakin.
As a duelist, he'd probably split with CW Maul.
All-out I'd place him in between Anakin and Obi Wan.
Some of this is kind of arbitrary.
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jk Bane sucks.