Let's see... Firsty, let's now count the Echizen family. READ THE FIRST SENTENCE: DON'T COUNT NANJIROU. And Ryoma is the love of Konomi, so he shouldn't be counted because he is only going to beat everyone sooner or later.
People are saying that Sanada gave Echizen a handicap because he only used 2 of the 4 counters. WRONG. If anything, Sanada was giving him a harder time... He only uses one counter on the people he plays. With Ryoma, he used 2. And Ryoma's win against Atobe... was GAY. There is no way in hell that a freshy could have more stamina than a senior, not even in Konomi's world... or, there shouldn't be.
With that being said...
Tezuka // Tachibana.
Tezuka lost to Atobe, ya. But he would have won if he used his Hyakuren Jitoku no Kiwami and Tezuka Zone to change the path of the 'World of Ice'. Tachibana (and I only assume this) beat Hyoutei in the tournament that they played in at the beginning of the series. Also, Sanada and Yukimura aren't up here because A) Sanada is stronger than Yukimura, B) Atobe would have beaten Sanada, C) Tezuka was using somewhat of a prototype (and had the shoulder thing) playing Atobe, D) Tachibana beat Atobe (again, this is only an assumption), and E) we haven't seen Tezuka play against Tachibana in his 'wild beat' aura. (I'd love this match).