And how can we know the multitudes of strangers in a mega church setting? As such, I believe in small churches of at most 100-200 people. That way, we will get to know one another and could possibly care for and love one another.
That's a very good size to me as well. Not as a law, of course, but as you say there is wisdom in it. If the membership is particularly close to the Lord, even a small house church of a dozen or two can likewise be great. Just depends on if they are open to the leading of the Holy Spirit and capable of being led by Him.