Currently we are using Mixpanel.com (YC company). Apart from usual figures like visitors, we collect information like user-engagement with a particular feature

Currently we are using Mixpanel.com (YC company). Apart from usual figures like visitors, we collect information like user-engagement with a particular feature. For example in our product we have a feature using which user can narrow results based on location and other parameters. We use mixpanel to track which parameters users select most, what combination of location selections etc. This enables us to understand whether user is really using a feature or not, and if they are, then how are they engaging with it. We hope to iterate better based on such data collection.