Chiefs because they've always been my 2nd favorite team after the Bears (also helps that they're in the AFC so them winning in the regular season doesn't affect the Bears in any way.) Arrowhead is cool and their fans are pretty passionate. Also I like Mahomes and it would be cool to see Andy Reid finally win one to cement his legacy.
I don't mind the 49ers at all though. I like how they have that old school philosophy of running the ball and good defense. Plus I've always liked their color scheme and uniforms. Should be a good matchup but I see the Chiefs coming out on top. I kinda compare it with the Bears vs Colts super bowl. Great offense vs great defense, and we all know how that one turned out
In the end the QB will make the difference and Mahomes is just at another level. 49ers gotta get the lead early to have a chance because I don't see them making a big comeback if they're forced to abandon the running game.