I grew into liking Google Analytics. When I started using it, it seemed too complicated--there is too much information, and you do not know what is relevant to you. The more I used it, though, the better I learned how to use it correctly. Also, their mobile app is great--it is even nicer to use than the desktop app.
BlueSnap handles our billing process but it has a lot of bugs. It is a well established company and we went for it because someone recommended it to us. Moving to a different service is very difficult at this point. We had serious issues with the integration with Paypal.
We started with JIRA because some friends recommended it. I do not have a lot of experience with other project management tools. It works fine, although there are several UX problems. Some things are done quite awkwardly. For example, if you want to add external links to your projects there is this awkward button that you click, and then you have to copy and paste your link. It feels very old school. Another example is that if you are creating a new project, you will see it on your project board only if you refresh it. Overall it works for us; it does not cost a lot and it is simple to use.