It’s more a personal decision, I suppose. I would find a theme that’s close to what you want and modify it to suite your needs.
Is it better to use the default theme because it is current with 3.0? Or, does that not matter so much?
Twenty Ten was designed in many ways to serve as a good starting point. You could start with the idea of completely modifying it, or you could also build a child theme based on it.
A child theme approach allows you to leave what you like alone, and only fiddle with what you want to change. The simplest child theme could simply consist of modifying the CSS rules in a child style.css.
Or you can modify header.php if you want to change the header, and so on. It really is a good way to start to build your own theme.
I built a child theme based on Twenty Ten that lets you tweak a lot of the attributes of Twenty Ten called Twenty Ten Weaver. I also built a very simple child theme that is intended to serve as a core for really building a child theme complete with theme admin panel. It includes a basic tutorial for building a child theme – available at the same site.
I built a couple of themes in the past, and building a child theme is much easier. Highly recommended.
