You don't have to choose a single option, even for a particular project. I've worked on websites/apps that have integrated 2 or 3 different server-side languages and frameworks. If you have a programmer that says "eww I'm not touching the WordPress part because it's in PHP" they just aren't the kind of programmer I want working on the project. Also, if you have a programmer that goes out an freaking re-implements WordPress in Ruby on Rails simply to avoid using a second tool, they probably aren't commercially viable and I don't want them either.