Besides Paul, Apollos and Cephas, whom did some Corinthians claim to follow?

Answer: Christ

Some said 'I follow Paul,' others 'I follow Apollos,' 'I follow Cephas,' or 'I follow Christ.'

“What I mean is this: Individuals among you are saying, “I follow Paul,” “I follow Apollos,” “I follow Cephas,” or “I follow Christ.””— 1 Corinthians 1:12 (BSB)