I've paid for KISSMetrics and really liked it. I know Mixpanel has grown, does anyone have reasons why I should use Mixpanel over KISSMetrics?
Also another good simple analytics service for all the different services you might use is DigMyData (http://digmydata.com/). I'm in a trial right now and finding it pretty useful.
Just curious, but what makes real time so important to you? What do you do with your data instantly that wouldn't be better served rolling up over a longer period of time to remove any noise-iness and natural variability in your data? I'm genuinely interested in your use case.
I've also heard that KISSMetrics is more about identifying people rather than data points, so it makes retention and user-based events easier, but it seems mixpanel does that too, so I'm not sure.
Also another good simple analytics service for all the different services you might use is DigMyData (http://digmydata.com/). I'm in a trial right now and finding it pretty useful.