I'm sure they all work well but to me the problem is consistancy. I trim today and maybe don't reload that caliber again for months or years. Then you have to reset the trimmer and adjust for length because you know you're going to trimming another caliber inbetween, and besides you forgot to write down what that length was.
The most consistant trimer I've seen yet is the Lee Manual trimmer. Yes most of you stopped reading with that, but the fact is there is no adjustment on this trimmer and therefore it is the same everytime, today, tomorrow, next year.
The problem with it, is the word "MANUAL". It's hard on your hands.
And the solution is have the cutter drilled and tapped for a stud/bolt that will match the power terminals of your RCBS or Hornady case prep centers. This allows you to trim, debur, and fully prep the case without ever having to change to another machine, and there's less wear and tear on your hands. And since the pilot pin never changes, neither does the trimmed length. And the same cutter can handle every cartridge that Lee makes trimmers for, and for I think less than $10 each