I'm building a Rails app that needs some data visualization. What is a good library to learn? (If it matters, I don't have much web/javascript experience, but I'm starting to learn.)
I've been dabbling around with Protovis... But, well, I don't understand what all the hype is. It seems quite long and painful even to create just a simple bar chart with axes, and badly in need of defaults! [But the only other real graphics library I've used is ggplot2 in R, so maybe this is standard for the web?]
I've seen gRaphael suggested, and the single piece example code I've seen on the website [for a piechart] makes it look much easier to use than Protovis. But there's no documentation, so I don't know how to learn to use it.
I've played a bit with the Google Charts API in the past, and it's fairly easy to use and well-documented, so maybe I should just stick with that if I don't need anything super fancy and customized?
So, I guess: what are the advantages/disadvantages of Protovis/gRaphael/Google Charts? Are there any other data visualization libraries I should be considering?