This is my experience. I have been making money online for like 10 years now. I started with Joomla, switched to Drupal and ended up in Wordpress. I will tell you why.
I loved Joomla at first. However, constant SEO problems, duplicate urls and other bugs made me to run away from it. I have only one site in Joomla now, but am trying to switch it to Wordpress. The biggest offence I experienced by using Joomla is that most of the modules are commercial, and these assholes want ridiculous amount of money each year for each module. So if you have like four commercial modules, you pay like 200,300 bucks per annum, just for one site. Furthermore, Joomla is very vulnerable to hacker attacks. Only Jomla was hacked of all of my websites. And once you let the stupid Iranian hacker to infest your server; he drips his doo doo on each site and injects the code etc. So you need to clean it manually, or if you have a backup. However, even cleaning the code was very long and hard process. Furthermore, Joomla uses huge databases, is very flexible, but even today they don't have correct urls for the seo. You still can't set the url name manually. It seems that the devs are still in the ice age era.
I then switched to Drupal. I loved it. I still do. It is great if you want a full-blown creativity when building your site. It is so easy to modify, there are no commercial modules that I know of. Everything is free. That is the biggest plus. There are all kinds of modules. Drupal is the best site if you have a massive server, and want a huge site, really complex. I mean whitehouse.com is built in Drupal for the god sake. It is practically hacker free so Iranian hackers are busting their heads how to hack it. I have to build several e-commerce sites in Drupal. Why? Because if it is excellent for whitehouse.com then it is good for me too. However, Drupal uses a lot of database resources. The tables become very huge. Each module that you install makes few tables in your database. So if you have a cheap ass host who allows only 1000 tables in your mysql total, then you are screwed, if you are building dozens of sites on one account. So normal Drupal site has like 200 tables, or more. So you can build like 4 or five Drupal sites on one hosting account. However, if the money is not the problem, Drupal is your solution. Nevertheless, it is not easy to maintain and also build. But once you learn how to use it will be very easy to build new sites.
So here we come to Wordpress. I had to switch to Wordpress because the database of each Wordpress site is really small. So you can squeeze like 50 - 100 sites on one cheap ass host. It is a very simple site, but why you need something complex like Drupal if you only publish simple articles? It is also SEO friendly. And most of the modules are free. However, you will need to buy a theme at least. So that is like 50 bucks, And if you have 100 sites, that is 5000 usd. But.....I hope you know what I mean by but...And a lot of modules are premium too, so you need to buy them if you need all full features. However, for me, where I build several sites, this is the best solution right now. It is very easy to build, just install it, then buy a theme, change banners, logo, and you are done...
So Joomla is still a doo doo, from my experience, and all the module developers are greedy plonkers so stay away. Drupal is completely free but as I said before the database is huge, same goes for Joomla. Huge database is the only problem I see in Drupal, and yes there are almost no commerial themes, Wordpress has a lot of them. So if your goal is to have 50 - 100 sites on one account, avoid Drupal or Joomla, because your host will close down your account. Stick with Wordpress for now.
Each of my wordpress sites has like only 10 - 20 tables per website. You can use the forum, thousands of articles, many modules and the site still stays very small. And if you are rich, have money for unlimited hosting accounts, go with Drupal, because it is the best CMS system around.