Magnets play a huge part in determining a good 4x4 from a bad one. Granted, magnetic cubes are down to preference, however they do also have alot of benefits.

We would recommend a magnetic 4x4 ✅

It's not just 3x3 that should corner cut well. All twisty puzzles need a little tolerance when it comes to aligning the layers and trying to make your next move. Corner cutting can be aided with correct speed cube lube and correct tensioning of your 4x4 but it's always good to start with a good base model.

We would recommend 4x4's that have more rounded corners on the pieces, back in the olden days this was known as a 'Florian Mod' but now comes standard on most 4x4's. ✅

It's always good to have a balance between the corner cutting of your puzzle, and the stability/control. Corner cutting gets better the looser your cube is, however, you do sacrifice stability and control (you are also more prone to your cube popping/exploding the looser it is).

We don't recommend loosening your cube to the point it falls apart just for you to have good corner cutting, if this is happening then you could potentially be due an upgrade. ❌