HipChat seems more oriented toward tech teams. It’s kind of annoying once you have more than a handful of people using it--there’s too much stuff constantly coming by, so people start to ignore it.
MailChimp is pretty easy to get up and going, and it’s pretty affordable. That said, it was hard to configure the way we wanted it--it’s hard to manage lots of overlapping mailing lists. Instead, Mailchimp wants you to have individual people only represented once.
We use Google Drive extensively. Generally we like it a lot (although managing permissions across tens of thousands of documents is overly complex), It’s really convenient because it’s tied so directly with mail/calendar that we’re already using anyway. When we chose it over Dropbox 4 years ago, it was because it was easier to manage both business and personal accounts. And then once you’re in it, the switching costs become too high.
We've tried everything: Basecamp, Asana, JIRA, Pivotal Tracker, Trello, etc. Nothing makes it easy to view everything on a single, old-fashioned timeline that we can use to see all projects at once. Pivotal Tracker is better for tracking agile software development and bugs, but not at all good for non-tech projects. Trello is better for rapidly putting together lists, while Basecamp is better at presenting mockups to a client but not so good for project management.
We’ve landed on Trello for managing development sprints and tracking upcoming projects, bugs and small enhancements. It’s not perfect but it’s less complex and has less overhead than some of the others (which means non-engineers also get up to speed and use it pretty quickly).