I use the Lee ones for .38spl, .357mag, .44spl, .44mag, .45 Colt, .223rem, 6.5CM, 6.5x47L, and .308win. They work very well. They cut inside and outside the neck and give the proper angles for each cut. I used to have a Giraud. Got rid of it because these work so well for me. They are fast too.
The cutting surface seems to stay sharp forever. I have yet to replace even one of them and I have used them for about 2 years now.
I must say that trimming is the least favorite of my reloading activities. When I found trim dies, it changed that for me. I really don't mind trimming now. I use them in a Lee turret press. And of course, proper measuring is paramount to not trim too much off.
Please don't flame me. To each their own. If some people have their own ways of trimming, good for them. This works for me.