Ask HN: Which analytics solution do you recommend?

Am trying to decide the analytics solution (client side) I should use for my startup thats about to be launched. A bunch of options seem to be available - Clicky, Mixpanel, Crazyegg, Google Analytics, Chartbeat, reinvigorate.net.

Which one would you recommend and why? Should I use just one solution or a combination? Any other solution(s) I should consider?

Can you also recommend best practices for a key-value store based server side analytics platform?