All my new sites are now on WordPress.com. Most of them use a free account. WordPress.com keeps the software up to date, protect it from viruses and other nasties, and makes regular backups of your data.
A paid site hosted by WordPress.com gives you more options and lets you choose your own web address. You can upgrade from free to paid at any time. This is less than $100 per year.
The WordPress program is free, and can be installed on a different site. Many of my friends do this with no problem. However, you are entirely responsible for updates, repairs, and backups. Not all plugins and themes are well-written. Many have security risks or won’t work with tomorrow’s technology. If your host upgrades their system, it might break the program. If anything goes wrong, it’s your problem, not theirs. Having said that, some hosts specialize in WordPress, and, like WordPress.com, will do the hard parts for you.
If you go this route, beware. Some hosts buy the domain name on your behalf, but register it under their own name. It’s in the fine print. If you want to move to a different host, they can keep your domain name hostage.
I used to use PmWiki. That program was great for its time. I still miss it. The code and database can be edited directly. Themes are simpler. The community is knowledgeable and supportive. However, it comes with the same downsides as installing any other software.