Legendary Legg Mason fund manager Bill Miller is seeing a variety of factors aligning to make this the best time for long-term investors to buy stocks since the early 1980s. Miller, who beat the S&P 500 for 15 straight years before falling on hard times in recent years, also tells CNBC that he’d “be surprised if the market isn’t up 20% in the next 12 months”, thanks to Federal Reserve policy, a strengthening economy, and “the fact that stocks are incredibly cheap” relative to bonds.