Honestly, it is much more important what the content is as it pertains to traffic. Without good content your traffic will always be marginal regardless of what type of hosting you are doing. As they say, "Content is King".
Personally, with everything else equal, I would always go for my own hosting. This way you have complete control as to what appears on your pages and if the site takes off and do start drawing a lot of traffic you can have control of advertisers, affiliates, etc. It would be a shame to dedicate all the time required to setup and build a good site and then lose the ability to profit from it if it became real popular.
It all depends on what you plan to do! Are you setting up a blog for you and your family? Chances are that the growth of that type site will be limited. Are you planning a technology blog? If you write good stuff and know what you are talking about, the skies the limit on that type of traffic. It all depends on your content.
There are many variables to consider. Think them through, be realistic in your expectations, study the market and competition and then only you can make the decision which is the best way to go.
Good luck.
