It kinda depends on what your goal is... Do you see your site being big one day? If so, you will probably want to host it yourself (or pay for it to be hosted).
Why you want to self-host: you have more freedom in changes, you can handle more traffic, uploads, downloads of information, etc. You can have subdomains allowing you to have the same "site" but to separate giveaways and reviews (to comply with BlogHer and the like). I have a subdomain that I test any changes so that my blog has as little down time as possible. You can have multiple themes running simultaneously. Ex: I am going to have multiple page templates running when I get my first ever toy guide!!! Would not be able to do that on blogger or blogspot... there are a lot of other perks, but many of them may not be relevant to smaller or more tightly niched sites.
Does that help?
