At least not now: While you may choose to put some money into a serious analytics package in the future (when you get millions of visitors per month and have specific measurement interests), there is absolutely no need to do that when you're small. It's just one more expense to think about.
If you don't know enough to choose one now (which is totally fine!) start with Google Analytics. It's free, it will do your sites, apps, and real-time stuff if you need it, your colleagues are likely to be familiar with it already, and it can cover A/B testing relatively easily.
When you find yourself saying things like "I wish Google Analytics had XYZ feature" or "GA isn't compatible with ABC thing we love" then you'll have a checklist for finding something more appropriate to your needs.
Otherwise, use the tools that come for free with services like Facebook and MailChimp! There are plenty of numbers in those while you're small.
Truly integrating multiple analytics package is — in my opinion — a solid opportunity for a start-up in itself, so if you're looking for a the one-stop-shop you probably won't find it. If you do, let us know! :)