It sounds like there are many different ones out there. I happen to use all Forster Trimmer products and have had very good results with Forster since I started reloading in 1982.
One problem is for very short cases, one needs the shorter base compared to the longer cases. I have the Classic, but I also somehow ended up with one that is shorter and one that is longer, so I have three bases mounted to my reloading bench. Of course, then there are the colletts which must be used to secure the base of the case and the pilot which centers the cutter head on the case mouth.
I don't know how others work, but I can tell you the Forster, once set for proper cutting length, will trim cases identically long.
At one time, I had the case mouth turning kit which trimmed the excessive brass off the exterior which flows forward and eventually makes the case neck brass thicker. There are also the inner case mouth cutters that cut the inside of the case mouth, also eliminating the excess brass that occurs.