I've done a lot of .30-06, .308, .30-30, and .223/5.56 over the years. Plus a little 7.62x25.
I've even done a lot of .44 Mag and .45-70 although they are straight walled in order to get a uniform crimp.
Doing 20 or 60 is not really a big deal.
Doing 200 starts to be a stretch. Doing 500 or 2000 at a time tends to get me a bit annoyed.
I started out using the Lee manual trim tool:
https://www.midwayusa.com/product/1012835597?pid=476992 Cutter and Lock Stud
Combined with a length gauge and shell holder:
https://www.midwayusa.com/product/1012838679?pid=107333
These work ok as long as you don't disassemble the length gauge and the cutter. Generally I've found that when they are reassembled there can be a change in the length even though the gauge threads are designed to scrape out any bits of brass in the cutter. The length gauges also are not the same from gauge to gauge of the same caliber. So you can't have a friend or your kid using a duplicate tool on the same caliber and get the same length. I still generally get one of these for each caliber although I don't have cutters for all of them. I usually use it with a power drill.
Wound up with a Dillon trimmer that came with a lot of other equipment. I have never really used it. Having to set it up on the press so that it resized and trimmed at the same time seemed like a pain in the posterior.
Picked up the RCBS trimmer back when it was the Trim Pro and came with the shell holder setup that required the individual plates for each family of cartridge and you had to buy a lot of the pilots and shell holders separately:
https://www.midwayusa.com/product/1012944415?pid=693746 It is now billed as the Trim Pro 2 and comes with a universal shell holder. I bought that as an upgrade when it was on sale at some point.
https://www.midwayusa.com/product/1012922384?pid=271401 This thing isn't my favorite. The pilots seem to be larger than the case mouths after resizing and I feel that works the cases. I've been getting tempted to chuck up the pilots and spin them against some emery cloth to turn them down slightly. It is also noisy and I haven't been extremely happy with the spring action that drives the cutter into the brass.
Lyman put out a E-Z trimer manual low cost trimmer setup similar to Lee's that I started out with but it uses standard shell holders.
They are available with multiple pilots in a handgun or rifle set and additional pilots can be purchased separately:
https://www.midwayusa.com/product/1012862472?pid=128681
https://www.midwayusa.com/product/1012883614?pid=799115
You can get a larger over molded handle for them:
https://www.midwayusa.com/product/1012874046?pid=512056 and they come with a cutter stud that came be chucked in a drill.
I picked these up at some point they were on sale for less than $20 for each set to see if they were any better than the Lee versions. At the time they were pretty inexpensive compared to the Lee versions.
The latest one I'm trying out is the Lyman Brass Smith Case Trim Xpress Case Trimmer:
https://www.midwayusa.com/product/1020728567?pid=258707
This one operates similar to the Frankford Arsenal version that GasGuzzler mentions above as it indexes off of the case shoulder although it is a bit more caliber specific and may be easier to set up and change the trim length.
Frankford also makes a version that uses the same collets as the case prep center GG mentions but is designed to be combined with a power drill. There have been some complaints about getting it trued up and the setup time but other reports seem quite happy with it.
Setup seems a common complaint on the shoulder indexed trimmers. Even the high end versions. The Lyman version I mentioned above cautions that brass sized at different times may not index consistently which makes sense. A different die setup or different ambient temp or even mixed brass lots could result in the shoulder being at a different spot compared to the case head. I've precision mic'ed enough brass to know that even in the same brass lot processed at the same time in the same setup the shoulder location can vary from case to case