Indeed I would opt beside WordPress but for the record I use pretty much all the major CMS platforms out there (the 2nd and 3rd most used CMS platforms are Joomla and Drupal - beside this I use other platforms like: CMS Made Simple, Magento, OpenCart etc.). I use them especially at work but also as a freelancer and for some personal projects too.
Indeed sometimes there are some small issues (bugs if you like with WP) but these are really minor things and usually updates are released in no time to fix any problems. Until now I can confidently say that I haven`t got any major problems with WP and I have also managed to pull off some complex website using it.
If we think about modularity (having in sight the costs) I stick to my initial suggestion of using WP. Joomla indeed it's pretty good, robust and modular but at some point I`m sure you will face a pretty common issue: either you learn some coding (PHP, CSS, HTML etc.) to develop your required features or spend some money on extensions/modules/components.
VS this issue, WP is really a community driven platform. Great support forum, plugins for pretty much everything you can just imagine. Just think about like this ... maybe you have a great news website and in time you form a user community and why not you may want to install an online community for them. Nothing easier, with a simple yet awesome plugin called buddypress you can extend your WP install into a fully functional online community. If we look at Joomla, you will have to spend a few hundred of $ to do this. Even Drupal is better then Joomla in my opinion. I mean I like Joomla's aspects, features and so but after a "few" project I can admit that the most satisfied clients had their projects developed on WP.
And thus at the first look WP may look simple and not so complex in features, I can say that it's just an impression because I bet you can't name a type of site that cannot be done with WP (from simple presentation website to e-commerce websites, online communities, multi-sites etc. etc.).
Also you don`t have to have to run 2 WP installs just to have a site with an attached blog. You can fully deploy a presentation website with an attached blog on a single WP install. Of course if you want to make sth like blog.yourdomain.com you can install another WP but also you have other possibilities too.
To brake it down in a few idea WP is straight-fwd with a great community behind (and a bunch of free stuff) and Joomla have a bit messy and complicated backend with a lot of great, but commercial/payed features.
I hope I managed to help you in some way ...