They're very different players.
In Madrigal, it seems to me you have a guy with a higher floor (near-certain major leaguer), but lower ceiling player. There's only so much damage a second baseman who hits 5-6 HR a year and doesn't walk a whole lot can do. He had better hit .300, or he's not close to an All-Star level player.
In Bohm, it seems to me you have a guy with a higher ceiling (impact power bat at a premium position), but perhaps a lower floor (likely major leaguer, but the bat doesn't play as expected and/or needs to change positions).
They're both good players. It's just what your taste is, how risk-averse you are, and for me at least, which is a better fit for the organization currently. I do take that into effect somewhat, because these are top-5 college players who should be in MLB in 2 years and not high schoolers 4 or 5 years away.
Having said all that...I think you have to take Mize if he's there, assuming the financials and medicals check out.