I think the Senju are superior, but not by a large margin as some people claim. The Uchihas were their closest equals. The reason for their slight inferiority is they are an Ocular and Spiritual clan, meaning their powers are based on spiritual beings in the Japanese mythos (i.e. Susanoo, Amaterasu, Kamui, Kotoamatsukami, etc.). Mangekyou Sharingan is needed for those kind of techniques and Madara and Izuna are the only ones that awakened it during that time. Without MS, the general skills I have seen so far from them are bukijutsu, shurikenjutsu, proficient Fire Element jutsus, and 3-Tomoe based attacks.
The Uchihas>Senjus claim was to me based off on the premises that their were 6 MS users (Izuna, Madara, Sasuke, Shisui, Itachi, Obito) and that there weren't many Senjus that stand out aside from Hashirama, Tobirama, and Tsunade. This is just from what I have read and seen.