I hate lead screws, if it was possible for my machine I would use belts.
I went through 4 lead screws to find two that were -almost- perfect, the instructions tell you that you attach the rods to the top and bottom using the supplied self-aligning bearings (this is an FT5 R-2 with dual lead screws with a single belt synchronized stepper) Having the lead screw attached in this way makes it almost impossible to remove binding, even then because you are restraining the Z screw from moving around to and fro- causes the bed to wobble- removing the top bearings helped with print quality.
lead screws are fine to be constrained in X-Y axis on say a CNC, this is because the axis only needs to be moderately accurate, but on 3D prints, especially decorative items, even the smallest amount of wobble is noticeable. Increasing the diameter of the lead is a double edged sword, on one hand, it will flex less under the weight of the bed, but on the other any variation of runout and out-of-round would force it's way onto the bed, rather than flex a little and allow the linear guides to resist the force from the leads.
I have almost no Z-wobble, but I have even considered going from dainty 8mm linear rods to 12mm rods to help mitigate this, in fact, I've toyed around with the idea to use 4 linear rails on 2020 extrusions as bed platform guides.
Ball screws are a possibility, but in order to get a quality part, you are paying an ungodly amount of money.
If I was to design a system it would have inverted lead screws, this way gravity pulls down on the bed instead of the lead screws fighting to keep the bed up, this would remove most all flex and would then only have to worry about the quality of the leads themselves.
