Having originally been a UDK user myself, I must say it is great that they are integrating visual scripting as a core feature of the engine itself. They are leading the way and setting new standards just as they did with node based shader editors, which Unity still hasn't caught up to. Luckily acegikmo has filled those shoes with ShaderForge.
I must say though, I believe Playmaker is leading the way on the visual scripting front. Unreal has likely taken a hint or two from the expanding popularity of Playmaker. The user friendliness of Playmaker combined with Unity just cannot be beaten. I won't be heading back to UDK anytime soon. I love Unity and Playmaker far too much!
I can't say that I have tried blueprint, seeing as how you have to pay monthly to use UDK now. I probably will sometime in the near future. I can say however that Unity is more user friendly than UDK in terms of learning curve. Playmaker integrates into Unity flawlessly. I wholeheartedly recommend Playmaker.
In the end a tool is a tool, and they will most likely share 90% of features. So use what you are more comfortable with, and make the most of it!