If I didnt already have either then I would get the 75B.Which would you pick if you didn’t already have either. A CZ 75B or a Witness in 45 acp? Both are in good used condition for the same price. No other suggestions allowed unless it is CZ(ish) for $450 or less.
Edit: Or 3rd option: Spend the money on training classes (and ammo) if you’ve never taken a class.
I would say that taking a class is very good. There is a lot of information to be processed. Even if you were to already know it all it would still be a good refresher.