I can’t see how he could possibly do worse.
On a scale of 1-10, while Trump’s Supreme Court nominees certainly aren’t 10’s, and I can’t begin to conceive of them as 9’s, but they are all higher than 4, which is better than Reagan or either Bush (all of whom did have at least a 9—Scalia, THomas, and Alito), but also had at least one clunker.
SCOTUS was as much McConnells' doing as it was Trump's. Trump had an incredible opportunity to place three justices on the Court but let's be honest, these justices were pretty much chosen for him by the Federalist Society.
The next President will likely get the opportunity to replace Clarence Thomas. He ain't getting any younger and would probably retire during the next Republican administration lest he makes the same mistake that RBG did. Again, it'll be the Federalist Society putting forth a list of suitable names.