I'm in the process of doing basically exactly what you describe - porting an older CF app that was written without any real framework to a cleaner CF codebase (also using SQL Server, BTW). We are using CF Wheels as the framework for this effort. We chose wheels because of a number of factors - we prefer the style of the framework, since it is similar to several other highly regarded application frameworks (Ruby on Rails, ASP.NET MVC, CodeIgniter, etc...). Also, the ORM layer wheels provides is quite nice, and will allow us to refactor much duplicated and verbose code.
I can't really comment much on ColdBox, since I haven't used it. Prior to Wheels, we were heavily into Fusebox. We were using Fusebox in a very structured MVC-oriented fashion, but as the Fusebox core lost momentum, we found that Wheels offered a similar organization to Fusebox (for how we were doing things) but in a nicer, more modern package, with lots of bells and whistles. So that is now our go-to framework.