The top ones would probably be marketo for marketing automation, hubspot for content management and salesforce for CRM.

Generating leads itself doesn't have to be complicated though. The message is more important than the medium. Whether you are using a tool within something like hubspot to collect leads, or have a private URL and are collecting emails on a clipboard (seriously), you are accomplishing the same thing.

Having the tools is less important than having something that resonates with your customer.

An analogy - when I was 11 years old I wanted to be a rockstar and became obsessed with guitars. I ended up dropping my life savings on a real Gibson SG which my idol, Tony Iommi from Black Sabbath had. To no one's surprise I didn't end up becoming the next Tony Iommi.

With lead gen, you can run circles around the best equipped marketer with a better understanding of who your ideal customer is and what he/she wants.

With something like marketing automation, the differences in tools start to make themselves known but it's really a matter of man hours vs. subscription fees at that point and the same ends can be reached, albeit with more work.

Shoot me a message if you want to talk about it (I'm doing all my calls free for the next bit)