The Maharil (Responsa, siman 95) relies on the Rosh that our Mesorah is better than that of others and the Mesorah of others is to be rejected in the face of our own.
Rav Chaim ben Betzalel, the brother of the Maharal, states (in his introduction to Vikuach Mayim Chaim) that even the rulings of the Ramo, representing Minhagei Polin, do not obligate the Bnei Ashkenaz as they have guarded their Minhagim carefully.
On the Aron HaKodesh of Worms was etched the pasuk (M’lachim 1, 19:4) “I am not better than my forefathers”, to serve as a warning not to change the Minhagim by an iota.
The Chavas Yair (M’kor Chaim 66:9) said that Bnei Ashkenaz are healthy like oxen from distortions and ruin in their Minhagim.
The Korban N’sanel (Responsa siman 5) wrote that Minhagei Ashkenaz are based on golden foundations and are better than Minhagei Polin. The great Rabbanim who spread Torah in Yisroel, like the Maharil and Mahariv, set for all generations all the stringencies and Minhagim which we Bnei Ashkenaz are bidden to follow.
Rav Yonasan Eibeschutz (Kreisi Upleisi siman 35) states that the Torah was passed on to the sages of Ashkenaz and what do we know that they knew not?