Best platform for a new website with CiviCRM: WordPress or Drupal?
I'd originally started my Civi 'journey' by bolting it onto our existing Wordpress site, and that was fine for holding contact details and sending out bulk emails/SMS. 

As we started to use Civi more though, it became quickly apparent that we couldn't do many of the things in Wordpress that we'd like to. The lack of an equivalent to the Drupal webform module was by far the biggest stumbling block for us (with the views module coming close behind). The ability to receive webform input directly into CiviCRM was key for us - we wanted volunteers and our clients to be able to input data in a way that Civi's profiles just wouldn't allow if we had stuck with Wordpress.

It was a fair bit of work (and a steep learning curve for me!) for us to transition across to Drupal, but the ecosystem around it and the sheer number of available modules has made it more than worth it. If I was in your position, as a new organisation setting up a new site, I'd go with Drupal in a heartbeat.