The answer isn't which type of traffic... It's how many traffic sources can you get together to make your numbers high while targeting your traffic best.
#1. TGP... Running your own gives you the option of focusing on a specific niche.. Niche specific TGP's convert better than general, and skim free does much better than a TGP that jerks it's surfers around.
#2. TGP/MGP submissions... Get together a nice submit list, establish a daily traffic base and focus on what converts best for you (templates, content, link placement)
#3. Blogs... This will establish bookmarkers, a daily reader base in which you will know what they want to see and you will start to have some SE trraffic to play with daily.
#4. Free Sites... Link List traffic is less quantity, but the ratios are generally better and the SE placements will be higher.
#5. Learn about SE's... Enough said.
#6. Collect names for newsletters. Be CANN Spam compliant, but milk all the information from your surfers as you can. A surfer you let do is 1 less surfer that you have a chance of making money with.