There are so many options out there, and every team has unique needs and wants. I thought I would showcase what has worked for the Pam Fergusson Charitable Trust (the organisation behind Voluntarily) instead of trying to tell you which is the best of the best!
We are a remote-first workforce with one physical venue (The Institute of Awesome). Our team is spread not only geographically, but also in terms of what types of work they do and how.
We have some "typical office workers", like the development and design team behind Voluntarily, some onsite staff at InAwe (catering, cleaning etc), some people that are out and about, but primarily work from home (like the team I lead, the PLD teaching team at OMGTech!). This myriad of things that we do mean that we have to have strict remote policies and work with them, no matter where the team member is located.
We use Slack primarily. We use it to communicate with each other, we use it to work with the many wonderful volunteers that come and go over time and we use it to plan projects and video chat.
We have both Google Apps and Office 365 at our disposal. As a technology charity that is lauding the benefits of technology, we prefer to be platform agnostic. So where we can give things a go, we will. We have all our emails on Google Apps, but have some stuff located in Sharepoint and do a bunch of our downtime buried in MinecraftEDU servers!
For our hardcore project planning, we recently moved from Trello to Asana. We found that the features of Asana were easier for our managers to keep track of things, but we still fall back to Trello for small projects from time-to-time.