Should I create lead generation sites, or local paid niche directories

I am very good at doing keyword research, and can rank local niche websites fast with very little work. I have just started creating a couple of lead generation sites, and within a couple of days I have them all ranking with hardly any content.

My question is for you people out there who already have experience with these types of websites. Do you think it will be more profitable to create lead gen sites that charge per call, or create niche based local directories and charge monthly for listings?

I am going to try out both methods for myself to see what works best, but I would love some input from people who have already tried these methods themselves.

When creating the directories, I will use EMD's and only create niche specific directories. An example would be a directory for plumbers in Dallas, or lawyers in Toronto. I would then contact a few businesses offering free listings to get the site populated, and then start promoting my paid listings options after I got some content on the site.

For the lead gen sites I also use EMD's, and create a Youtube video promoting the service my website is about. I then put up a phone number that redirects to a business every time somebody calls it.

Any input would be greatly appreciated. Thanks!