Both are excellent coaches. Ancelotti has proven himself many times, while Xabi is just starting his career. I think Xabi has great potential for the future because he is still young. Their playing styles are also different; Xabi relies on a style that prioritizes ball possession and attacking. Unlike Ancelotti, who focuses more on combination plays and doesn’t prioritize ball possession.
Ancelotti is one of the best coaches of all time, with extensive experience and a flexible philosophy, enabling him to handle teams with various characteristics and win major trophies in different leagues. Therefore, Madrid should give him more time. At least three years should be enough for him to build better trust with the fans and management.
I don't want to downplay Xabi's achievements, but compared to Ancelotti, he is only at the very beginning of his journey and he still has to prove how good a coach he is. He created a small miracle with Bayer, but he couldn't repeat it in the new season, and Real is a completely different level and I can't say yet that he is ready for a team of this level, at least if we evaluate his work in the Club World Cup. In La Liga, there is Barcelona, which is in excellent shape, so it will be difficult for them in La Liga too.