If I have a CSV of a number of values (say in the thousands), and what I need is basically a tool that will create a slick, good-looking graph that compares two or more of these CSVs, what's the best tool for that? Think JMeter if that rings any bells.

I honestly just used some basic graph-generation tools which would spit out PNGs, which is always less than satisfying. I looked at Grafana, but never had the time to actually try it out. My feeling also was that it was a bit different of a use-case as I had no real-time data, but I may be totally wrong here.