We've had really good experience here at Business-Software.com with Wordpress.
That is a pretty open ended question. I think it would depend on the size of your company, the capabilities of the staff and your ultimate goals. Iciniti Corporation has had a great relationship with Sitefinity CMS by Telerik for about 3 years now. We chose Sitefinity as a development partner because our technology was aligned and they had excellent tools that allowed us to extend the product to add our ecommerce application. The end product has been very well received by our clients, who have found the Sitefinity management tools powerful and intuitive. So from my research, if you want an excellent .NET CMS that is easy to extend - Sitefinity is an excellent choice.
You should also look to the company designing your website (if not done internally) to make a recommendation. Especially if you are not "married" to your current CMS.