If you’re setting up a portfolio with possibly a few extra features in the future, don’t go buying a truck when a bicycle is what you actually need.
As stated Wordpress is easy to set up, extremely popular (by a quick look at some statistics, easily trumping the rest) and well documented. It’s also being used by really big organizations, so it’s extendable if need be. My own site uses WP and I have no complaints, though i haven’t really followed the development of the CMS for the past couple of years.
Blog was a big feature for me back in the day (I migrated my blog from Blogger, and never looked back), so WP was a natural choice but for many artists and illustrators an even simpler CMS with good gallery plugin(s) and effortless usage is often enough.
If you have to wonder about needing a feature, you’re probably not going to use it in the long run. If you think something won’t be too much of an extra hassle (when there would be a simpler way), it will be. Make sure the process for updating the site is as effortless as possible, or else you’re not going to do it very often once the novelty has worn off. Been there and seen it happen to numerous other sites, commercial and private. But having said that, it’s also good to know that you will be able to extend the functionality (like with a store) if need be.
So the bottom line from me is, get a CMS (manually updating is a bitch) that you feel comfortable using and also pick one that suits your needs. Ask Google about CMSs and go to opensourcecms.org and try out the demos. They have countless free CMSs to try out, including Joomla, Drupal and WP.