There is no debate whatsoever that Yamamoto has the most destructive power in all Bleach thus far. His Shikai has enough power to wipe out cities / His Bankai has enough power to wipe out a dimension.
Yamamoto vs. Hog. Aizen comes down to Kubo's plans about the whole 'transcendent reatsu'. If it's "transcendent reatsu > ALL reatsu" then yes, Yamamoto is the weaker. However, if transcendent reatsu is simply another type of reatsu that unlocks 'off-limit' abilities, then no Yamamoto is the stronger.
And really, if "transcendent reatsu > ALL reatsu's" then Gin would have not tried to stop Kyoka Suigetsu, what's the point of stopping KS if Aizen's reatsu would trump Gin's anyways? Again, this is the same character who witnessed Aizen destroying the cleaner, yet his main worry was Kyoka Suigetsu, not "Aizen-sama's ever so godly reatsu".
Besides really if we talking about unability to sense reiatsu than Royd wasn't able to tell where the flame of East went aka he couldn't sense a reiatsu made flam. Neither was he able to see and sense east before Yama actualy allowed him to see it and even than Jugo needed to actualy think before comming up with the idea that the flame is reiatsu and he just came up with it and not actualy sensed the feeling of reiatsu.
This is one of those vague, gray areas in Bleach. Basically, Aizen declared that he was a transcendent being, but he never really gave an idea of what that means, mentioning only that his reiatsu could not be felt by anyone not on his level. However, then comes Ichigo and Aizen can't feel his reiatsu, which he tries to claim is because Ichigo gave up his reiatsu for physical power, but Ichigo pretty much disproves this instantly. Aizen could not fathom that Ichigo could also be a transcendent being so thats where we are stuck. You could say that Ichigo had gone to a level even higher than Aizen and thus were both transcendent beings, or you can say that there is no such thing as a transcendent being. Frankly, I believe that the whole transcendent being thing was just Aizen being full of himself as usual, but the story never really clarified itself one way or the other.