We use Groove also. It works fine but we do wish it had any kind of mobile support. Even if the desktop site would just function in a mobile browser would be helpful. Two way Slack integration would be a dream (it has notification only now. You can't respond to tickets from slack).
We switched to Groove from Zendesk (which was awful). We're happy with it. I do wish it had better reporting. It also has occasional hiccups (missing emails, report numbers inconsistent).
Groove is who I went with, after looking into this area. Very happy with it so far, the on-boarding was perfect with its step by step setup. Would certainly recommend.
We have used Groove and really liked the simplicity of the software. However as use cases matured we realised that doing SEO on the knowledge base articles is not possible.