I spent 2 years in Marketo and am now working almost exclusively in Salesforce Marketing Cloud. I've used Pardot as well and will say that SFMC is very different than Pardot.
As far as advantages of SFMC over Marketo, I think a lot of it depends on the use cases for your business. I think Marketo is an awesome tool and can make things easier when it comes to standard marketing tasks like sending emails, lead scoring, and managing marketing data.
One advantage for using SFMC is the ability to manage Email, Content, Mobile Messaging, and Social Media within one platform. In my experience, Marketo requires using plug-ins and integrations with other platforms for functionality outside of email sends (like sending SMS/Push messages). Another advantage is the ability to have complete control over your data model. If you have a complex data structure, I think SFMC is more flexible (but also has a steeper learning curve).
As far a integration with Salesforce, I had a great experience using Marketo. I think you can get a similar experience using Marketing Cloud Connect but it does require some configuration and process changes. Once in place, the integration between SFMC and Sales Cloud can be pretty powerful, especially if you have complex use cases.
Overall, I think Marketo is easy to use, has great integration for most standard use-cases. SFMC is better for larger, more complicated environment, especially if you are already heavy Sales Cloud users.