I have had two commercial P&P machines over the years. First I got a fully functional Philips CSM84 (made by Yamaha) in 2007. It came from an operational contract manufacturing line who was highly motivated to sell as he had new machines coming in 2 weeks. It was VERY easy to program, and the manuals were quite good. But, it used mechanical centering jaws and was not quite accurate for fine-pitch parts.
In 2020 I got a Quad QSA30A from an auction in Texas. This was made by Samsung, but fitted with Quad electronic feeders and Quad alignment cameras. It is a LOT more complicated to program, but works amazingly better! The manuals were TERRIBLE, but I got hooked up with the guy who did training at the factory, and he was a HUGE help!
Anyway, one of the biggest parameters to consider is the number of feeders a machine can hold. And, remember that feeders for wider tape will take up several slots on the feeder rails. Second is availability of, and durability of, nozzles. Cheap plastic nozzles will wear pretty fast or break when there is a mis-pick. My first machine did not have a nozzle changer, I really didn't know what I was missing!
My first machine had spring-powered mechanical feeders that were too weak to peel some cover tapes. Feeder jams were extremely frequent. I tended to put C-clamps on the empty tapes to provide more pull to help the tapes advance and peel.
The electronic feeders on the new machine have plenty of pull to keep those tapes working.
Another think to look at is error recovery. My old machine would just stop after a few mis-picks of one part, and wait for you to fix it. The new machine detects a few mispicks and marks that part as skipped, then when it gets to the end of the program, it beeps, waits for you to fix the issue, and you press start and it places all the skipped parts.
If you go for a used, commercial machine, make sure it is a commonly-made model, and parts will be available for some time. My new machine was made around 2000 but parts are still VERY easily available for it.
Jon