Re: Itachi's the strongest uchiha after Madara.
As far as Chakra prowess go, then Sasuke has the most powerful chakra that is above Madara's according to Kurama, when the latter had an exceptional clan chakra to begin with. How cn you place Sasuke so low is beyond me. According to Kabuto, Orochimaru, and Obito, Sasuke has more potential than his brother and thence, surpassed Itachi when he gained a bit of control over his MS let alone EMS.
On Power levels Sasuke has EMS that is the ultimate ocular form of sharingen without any cellular addition. Madara has EMS as well, together with perfected form of CS, called PS, and Obtio has his S/T jutsu manipulation Kamui that works in two different ways.
On chakra grounds: Sasuke > Madara >>>> Obito >>>>>> MS Itachi
On Power Tier: EMS Madara >>Obito> EMS Sasuke >>>>> MS Itachi.
Compared to current Uchihas, Itachi is much much weak. He is no where near their level now.