Salesforce Marketing Cloud is the marketing automation product from Salesforce. Packed with features, it works perfectly for organizations already using the Salesforce CRM.
If you compare Salesforce and Marketo in terms of features, Salesforce is clearly the better choice. You get better social media and emial automation capabilities. Salesforce is also better at handling and segmenting data at scale. It also integrates easily with Salesforce CRM, which is still the best CRM solution on the market.
The problem is that Salesforce Marketing Cloud is hard - and expensive - to buy. Don't be fooled by the $400 initial price tag; for any meaningful package, you'll spend thousands each month. It is also not particularly user-friendly for small businesses.
If you're a larger business and have the resources to support a Salesforce deployment, it can be a good alternative to Marketo...Full Salesforce Review