We went with Digesto. We didn't want the mailchimp logo on the footer of the emails. Also because we target the different RSS subscribers for specific promotional email campaigns, we didn't want to have to import lists from Mailchimp to Marketo. Cleaning up unsubscribers and bad emails will have to be done in two places, and it's just not practical.
We use Digesto as well and I like that everything's all in one place - you can reach out to me if you have any specific questions