Cleveland is better regarded than Taft, so he wins.
What makes you say that? TBH, I don't think most Americans know too much about either President, so Taft can just paint Cleveland as an extremist who opposes Medicare, Social Security, and women's rights/suffrage. Cleveland could always flip-flop, but YouTube would ensure that he would never be able to fully run away from his past.
Taft is concidered one of the worst presidents, Cleveland near the middle.
Taft isn't ranked as one of the worst. He is typically ranked just a little below Cleveland. Besides, those are the viewpoints of some historians. Most Americans don't know too much about either of them, and thus each of them would have a chance to redefine their image and reputation. That's not to say that some bad things about their past won't come out, though (like Cleveland's staunch opposition to women's suffrage).
William Howard Taft also opposed women's suffrage.
Thank you for revealing once again that trying to force historical politicians into a modern setting is an exercise in futility.