One of the best and easiest ways to check on plotter quality is to check if they utilize steppers or servos. The servos are by far the best.
The next thing to look for is pressure capability. Most of the cheaper Graphtecs, and Rolands, go to 300. For most people 300 is fine. If you think that you may need to cut things like sandmask, then you need more pressure.
Speed is a matter of preference. Ours is capable of 31 ips, but we never run it that fast. You will want at least the capability of 16 ips - no less.
Most are capable, and equipped with windows drivers, allowing you toi cut with Corel and Illustrator - some of the cheapest and widely used software available. Do not sweat the pro sign making software, until you get the feel of the process. Most of us use a combination of software.
Stick with a name brand such as Graphtec, and you cannot go wrong.
As for used plotters - new ones are too cheap, to consider used.
