My only experience with trimmers is with the Lee trimmer where you put the case holder in a drill, and a Forster hand crank trimmer.
I don't like the Lee because of the concentricity problems: no matter how hard you try, some of the brass will not sit properly in the case holder and the case spins off centre.
I really like my Forster trimmer, it's exact, always on centre, very smooth feeling. My next acquisition will be the 3-in-one trim.chamfer/debur tool that attaches to the Forster so I can do it all on one machine.
You can also buy an attachment that allows you to motorize the Forster.
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