Pardon me for being frank, but that is a rather stupid question. Of course, the head of all is Christ Jesus. The leader of the Church on earth is His vicar, the pope. Just as Jesus himself set up when He gave the keys to the kingdom to Peter.
I have a question for you. You say your litmus test is scripture. Are you a proponent of Sola Scriptura? If so, where in scripture does it say that scripture is the sole authority? And what did the early Church use for NT scripture since most of it was not yet written?
The scriptural justification for papal ‘vicarship’ is also questionable. It’s rather late and I’d rather not get into it now, but if you look at the Greek of the most commonly used supportive text, it does not refer to Peter as the ‘rock’ in a way that denotes that he is the physical rock (please correct me if I’m wrong).
It also ignores other scripture where Peter is chastised... for instance where Christ rebukes him with, “Get behind me, Satan! You are a stumbling block to me; you do not have in mind the things of God, but the things of men.”
(Mt 16:23)
Please note that I am not saying Peter is Satan... he remains an Apostle of Christ and one of the foundations upon which Christ spread his Good News.
As to ‘Sola Scriptura’, except in discussion with Catholics, the term never comes up. It is often used as some kind of condemnation... as if a it is somehow wrong to base your faith entirely upon the Word of God. What a sad thing when people use trust in scripture as an attack.
I do not look only at scripture however, and I think you'll find this true of even those who claim adherence to 'Sola Scriptura'. We all look at the writings and lives of Brethren in Christ, both past and present. For example, I usually have at least one missionary biography going at any given time, and also look at the writings of early Christianity (ie Tertulian, Justin Martyr, Augustine of Hippo, etc). More recent theologians and thinkers also top my reading list (ie. Ajith Fernando, NT Wright, John Dominic Crossan, etc). I should mention that merely because I read them does NOT mean I agree with everything they write.
I absolutely affirm though, that the highest authority is the Word of God contained in scripture. It is scripture that I use to measure the people that I read.
We are to use the Words of God to test the wisdom of man... not the other way around.