For an enterprise .NET CMS, our platform of choice is Sitecore.
From a development standpoint, it is very easy to get started with Sitecore, whether you've done ASP.NET development with WebForms or with MVC. If you're transitioning from Umbraco, many concepts transfer over without many changes.
Content editors and business analysts love Sitecore because it gives them the ability to easily add and edit content either through the content tree or the page editor. It also gives them the ability to configure workflows and set up granular security.
Umbraco is a great choice for a simple, more affordable CMS to build your online presence or manage content for your web application.
To contrast Umbraco with Sitecore at a high level, it is more affordable but offers fewer enterprise level features. However, from a structure and usability standpoint, they're quite similar. Umbraco has built-in support for building views in Razor and even supports MVC. A strength of Umbraco is that due to it's more concise feature set and community driven development, it's able to adopt the latest .NET technologies faster than the alternatives.
Many people appreciate the simplicity of Umbraco CMS and choose it for this reason. It works well when you want to get started building quickly and don't need tons of features and plug-ins. For many applications, Umbraco's focus on the basics makes it a great choice.