Acquia has produced an excellent top 10 list of "Reasons to Choose the Drupal Open-Source Social Publishing System" which should be enough to convince anyone just how powerful the Drupal CMS can be to meet your needs.
The abbreviated list:
1 - A platform for rapid website assembly
2 - Enormously scalable
3 - Freely extensible
4 - Built for social publishing
5 - Open to your branding
6 - Flexible in deployment
7 - Beloved by a thriving development community
8 - Without software acquisition or licensing costs
9 - Fanatical about following standards
10 - Proven high in security
We can find no fault in this list. In fact, we agree whole unequivocally, but let's take some creative liberties and expand this to focus on some non- "high-level" reasons to choose Drupal.
- Extensive support network — Worrying about in-house support of custom projects just became a thing of the past. With a community responsible for more than 15,000 contributed modules, building a site using the same foundation as thousands of other sites has never been easier.
- "We've done this before" — Custom needs aren't a hassle. In fact, a key part of Drupal is its ability to take an established concept and allow each site to morph it into its own needs.
- The right piece to the puzzle — Often web solutions can feel like trying to shove a square peg into a round hole. With Drupal, finding the perfect fit to a need is easy. No more compromises because a solution is "close enough", Drupal's powerful and extensive community has the solution to any need.
- You don't have to be a developer to use it — Drupal allows us to build solutions for the average user, not just the power Internet users. A solution can be as complex or as simple as needed, and without all the "bells and whistles", if so desired. In short, Drupal lets you tailor your site to your needs, not someone else's.
- Agile enough to serve a single 'about us' website, or deliver an entire e-commerce product and solution — Start small and dream big, or go big out of the gate. Drupal can accommodate any digital and online strategy, no matter the scale. From the biggest sites with millions of page views to the smallest local startup, all businesses rely on their websites to be there for them and provide exactly what they need to their audience. Drupal doesn't let anyone down in this regard.
And a bonus reason . . .
It's only getting bigger — Drupal's share of the CMS market is exploding, and there are good reasons for that. With all the bonuses to choosing Drupal mentioned above and the ever-growing community of people providing open source solutions free for anyone to use, it's hard not to see how such a platform wouldn't be welcomed with open arms. Drupal is a powerful solution that can provide powerful results, and it's only getting better every day.
What would you add to the "why choose Drupal" list?