My friend and I used Kickstarter for our first volume and it was a great success. About 40% of our backers seemed to have found us through Kickstarter itself, so on top of the money we were able to reach a bunch of new fans. We're planning to go with Kickstarter again for our second volume.
I've never used Indiegogo but I've heard that it has some good marketing tools. Its rules about what you can and can't post as a campaign are less strict than Kickstarter, so you can start raising money before having any kind of prototype. You also can choose to keep the money you make even if you don't reach your goal, which is good for creators, but some people don't trust that.
Personally I prefer Kickstarter. It's bigger, has stricter standards, and I would never pay into a campaign that keeps the money even if they don't make goal (thus might not be able to provide the service they promised). But I would try to ask some of your readers if they spend more time on one or the other, if you're curious about their preferences.