Other than forex, stock CFDs are probably among the most popular trading instruments for retail traders today. They are available on a large number of companies, in particular the largest publicly traded companies in the US and Europe. Almost all CFD brokers offer stocks of at least a few large companies to their customers.
The main benefit with trading stocks as CFDs is that they come with built-in leverage, which makes it easier to make meaningful profits (and losses) even with just a small trading account. In addition to that, CFDs also make it very easy to make money by shorting stocks that are going down in price, which is something many traders enjoy doing.