Lead generation is critical to filling the sales funnel. As such, we do a lot of demand and lead generation work for our business-to-business (B2B) clients. When I came across the 2015 State of B2B Marketing report from Salesforce Marketing Cloud, I had to check it out.I'm always interested in learning more about new strategies that can help our clients develop better leads and then convert them to grow their brand preference and sales. So I headed straight for the section that covers 2015's biggest challenges.The report, which surveyed more than 2,100 B2B marketers, listed the top 3 B2B challenges as: Growing new businessLead qualityDemand and lead generation