I am going to break the trend and say flat out that I prefer to build an HTML/CSS site instead of Wordpress.
Everyone tells me that google loves wordpress, but I disagree. I have never had a harder time ranking any HTML/CSS site over wordpress, and IMO HTML/CSS sites are better in the long run for customers with no tech skills.
WP is a hackers dream, security is a nightmare, and backups of complicated sites are difficult too. it needs to be updated every time an update comes out for the theme,a plugin, it he installation itself. I actually had a site just decide to quit displaying due to an un-updated plugin that had a reliance on something in the installation. Had to call bluehost to figure out the offending plugin because when it happened, it would not log on any users. They had to go into the server and delete the plugin just for me to be able to regain access.
Unless you are a developer, it will drive you buggy trying to get t to behave right. When you do something the way it was supposed to be done and it doesn't work,you are screwed. I have one plugin I use that floats images left, right, or center on many themes, but on others, it doesn't float the image, it puts it at the top and the text below it.
Duplicate content is always a problem if you set your pages up wrong, or assign posts to multiple categories, unless you understand using canonical pages correctly. Couple that with forgetting to forward your non www site to the www version of your website and you can end up with a duplicate content penalty you do not even know you are getting.
Small changes to the Theme are difficult,and can break the theme.
SEO is a bitch with WP and almost everyone thinks it is just a matter of using a plugin. Sorry, there is a hell of a lot more to it than that.
Another problem is the heading tags. WP developers tend to use them to control font size instead of SEO. They either do hot use the H1 tag, or use it multiple times. If they do not use it,and only define H2 tags in the CSS, when you use an h1 tag the font looks like you are building a page for a blind person. Even wprse they use the H1tag for your logo, which gives every page in the site the exact same heading.
At first until you understand default behaviors, even when you do not put something into a sidebar, the theme will populate it with whatever the developer decided to stick there.
WP is an easy way for people to build a website, but most WP installations I see are an SEO nightmare.
WP uses a lot of server resources, and the more plugins you pile on the worse it gets. The more sites you have on the account the worse it gets.
Load times are terrible, especially if the user does not re size the images before using them.
An overlooked SEO metric is the amount of text to code on a page, and WP tosses a lot of code for every function it uses.
Personally, to me its a quick way to build a default website, and you are doing a disservice to your customer dumping him with a wordpress site, especially if you do not stick around and teach them how to maintain and use the installation, or have a contract to do it yourself for them.
And for the record, I do build WP sites.
As I said, just my opinion.