We are currently looking for an inexpensive and easy to use dialer and email cadence tool which integrates with Salesforce and syncs to Marketo. Out of the box MSI is great but we are looking for a cadence tool that is a bit more robust.
We have demoed tools like Outreach, InsideSales, and Groove. What is your org using?
Depends on your needs and budget. What sort of programs and reports are you looking for? Integrations?
Outreach is pretty good. ToutApp or "Sales Engage" is similar and from Marketo.
IMO, you can do 80% of this in Marketo with no additional purchases. The Dialer or in-line task management is the only area that you would have to add on. Some people look at diff reports in Salesloft or Outreach as well, but I'm not convinced this is totally necessary.
Try to build and test it in Marketo FIRST, then decide if you need to scale it with another tool.
Our sales team uses Groove. I know a lot of people like Outreach too.