This is a bit tricky question. My answer is both. However you should aim to create a “brand name†for your blog first. If you build a successful “brand name†for your blog, this will also support your personal branding. Also it allows you the flexibility to invite other authors in the long term. This makes your blog a more profitable asset, since it is not tied to your personal brand.
If you still insist that blogging is a one man show, then i suggest you to start thinking out of the box. I believe by being the only writer you are limiting the growth of your blog and also creating a commitment you may not necessarily want forever.