Board Thread:Naruto Discussions/@comment-28861328-20140618060932/@comment-1512913-20140703222142

Uchiha and Senju were 2 strongest clans, let's leave it at that, irrelevant which was stronger. Also members change over time, so at one point, either was stronger than the other. After Hashirama and Tobirama died, technically Uchiha were stronger, since Madara was still alive :P although no longer as a part of the clan, though.