Tanjiro is a demon hunter just like Ichigo. Their circumstances are pretty different but the end goal is fairly similar. Ichigo had to deal with finding out that he was part demon and even had a third race mixed in though. Along with this came his FullBring powers so by the end of the series Ichigo really just had every kind of power possible. Bleach as a verse just gets a lot crazier than Demon Slayer so by the end of the series it just wouldn’t be possible for Tanjiro to keep up with a guy like this. Ichigo’s just too insanely powerful. Ichigo wins.