I think Zinchenko's better. He's put in big performances against the likes of Liverpool, Spurs, Chelsea, United, Arsenal, Dortmund and not made a mistake, and been part of a very solid defence up against some very good wingers.
Cancelo has made mistakes, he cost us the Leeds game only a couple of weeks ago.
Also Zinchenko being left footed makes a big difference when it's Dias and Stones in defence. We saw how bad our build up was against Dortmund with Cancelo LB, and Pep called it out after the game and used Zinchenko in the second leg.