Which is better for Friday Prayer: a small mosque with a sermon from Ahl as-Sunnah wal-Jama'ah and few worshippers (10-20), or a large mosque with irregularities such as two Adhans and an Imam who commits some irregularities, but a large number of worshippers (200)?

Pray in the congregational mosque (Jami' Masjid) where the number of worshippers is large. There is a difference of opinion regarding the validity of prayer in a mosque attended by ten to twenty people. As for the two adhans (calls to prayer), the second adhan on Friday is a Sunnah, and the first adhan was instituted by Uthman, may Allah be pleased with him, and his Sunnah is to be followed. The fact that the Imam commits some violations does not invalidate prayer behind him, unless it is a disbelief-inducing innovation.