Salesforce is a pretty pervasive tool; this means that you can find a lot of online resources for troubleshooting. The ecosystem around this tool is very strong. It integrates very well with all the other tools that we use, as well as Terminus, our own platform. For us, it’s very important to have our tools integrate seamlessly with one another as much as possible.
We use Slack for both internal and external communication. We have a community of people that we built through Slack. Slack is very easy to use - setup is really fast and you can add groups quickly. The only negative aspect is that at the moment it does not have threading, so it does not let you track your discussions very easily. The message that you were interested in can get buried in other messages very quickly. I believe that they are working on implementing this feature.
We use Terminus, our own platform, to do account based marketing: If you want a company to adopt your tool, instead of targeting just one person in the company, you are able to create advertising campaigns that will target the entire set of people that are involved in the decision making process.
Trello is simple and multi-purpose. We use it to organize any type of project, including our hiring process. We really like the calendar functionality because it allows us to keep track of what needs to happen on any given day.