I work on web analytics for several startups here is the general trend.

Google Analytics is the most basic one they start with because its free and easily extendable.

Kissmetrics or Mixpanel for extended time period analysis (cohort, churn, clv).

Mailchimp and Visual Website Optimizer offer one click integration with GA. Mailchimp can be integrated with KM too so that helps tying the data together initially.

Usually once they setup KM/MP they use it for day to day and keep GA as backup. But alot of times you'd find yourself going back to GA to measure impact of an action that you werent tracking in KM.