Had anyone used a Salesforce custom connecter that you can recommend, that pulls in SFDC standard fields in Marketo?
There's nothing better than the built-in SFDC sync — frankly one of the best cross-vendor integration features of any enterprise platform, not just marketing automation.
More to the point, nothing else will ever be, because you can't use the SFDC & Marketo APIs at scale.
What exactly are you trying to accomplish?
I agree but in some cases you can't use the default connector (such as when you want to connect multiple Salesforce's to a single Marketo instance).