If you are looking for better branding possibilities than what you currently have in SharePoint, than you will love migrating to SharePoint 2013 or Office 365. Branding is one aspect of SharePoint that has seen many visible improvements in the latest version upgrade. The most noticeable one would be the disappearance of the Design view in SharePoint Designer.
Summary of new branding features of SharePoint before migrating
If you've downloaded the 111 Hot new features in SharePoint 2013 eBook, you might have quickly seen these changes. Let's go over some of the new features that have the most impact on our branding possibilities.
The Design Manager
I could probably write an entire article on just this, in fact I wrote a few to help get started with branding. Not to be confused with SharePoint Designer, the Design Manager is more of a set of features than an actual tool. When activated through the Publishing Infrastructure feature, the Design Manager will allow you to:
Convert an HTML page into a Master Page
Convert an HTML page into a Page Layout
Add code snippets using Snippets Gallery
Associate a Master Page to specific Devices with Device Channels
Work from Mapped Folder using any HTML editor
Create a Design Package to deploy
The obvious change is the one that allows you to use any HTML editor right from your desktop with a mapped drive. Designers can now work with tools like Dreamweaver and build a regular HTML page to be used as a Master Page in the future. Then, upload it and convert it into a Master Page while adding any Code Snippets necessary from the gallery. After all that, the creation of a WSP package to deploy it can be done straight from the interface offering a complete set of branding features of SharePoint to implement. The Design Manager is one very good reason to migrate to SharePoint 2013 or Office 365.
Design View disappearance
It won't surprise you by now to find out that the Design View in SharePoint Designer is no longer available. There is obviously the Design Manager, that tried to be a replacement allowing to work with other HTML editors. However, if you were using it to edit your XSLT Data View Web Part or apply conditional formatting then you will be disappointed. There is no real replacement for those, though many will argue, the other solutions aren't as "easy to use" as the Design View was with SharePoint Designer.
Are the new branding features of SharePoint 2013 worth migrating?
Definitely one of the main reasons to migrate! If browser support and flexibility of branding is important for you, you will love the new version. SharePoint 2013 has been rebuilt with HTML5 support and works just as well on Safari, Chrome, Firefox and of course Internet Explorer. It allows you to build in HTML and convert it into a Master Page or Page Layout without dealing with pesky XSLT and even allows you to provide reusable templates with almost everything. When I first saw SharePoint 2013, the first thing I did after upgrading was play with the new Design Manager and the branding features available.