From experience of using many type of DAWs I would say that FL Studio (formerly know as Fruity Loops) is one of the easiest to use Digital Audio Workstations.
The reason being is that myself and many others have been able to produce decent quality music without having the to refer to the manual or Google anything. I really do believe that you can cover around 80% of the functions just by playing around, and beats can be made instantly. The design of the FL Studio Digital Workstation seems to fit the electronic music genre, however you can make tracks of other genres e.g. R&B, Soul and Hip Hop no problem.
Just like some vintage synthesizers you are able to make beats by simply flipping switches on or off. If it sounds too tight then you can add swing or a humanize factor to the tracks to give them more of a natural feel. For melodies, you can just play live and edit afterwards.
FL Studio supports multiple tracks and best of all VST plugins which make it a complete Digital Audio Station. VST setup is pretty simple, you just need to define which directory the VSTs are in, from the preferences menu.
I use FL Studio a lot for my game projects which I have been working on recently. I can bang out a decent 2-3 min electronic house type track in less then 30mins. I just put that on loop and have it as background music.
Another very easy to use function for the Digital Workstation is the pattern arranger. The main screen represents the number of bars for a short section. You can take these bars, and put them together in the pattern arranger screen without having to copy, cut and paste anything.
Reason is another very easy to use Digital Audio Workstation, however it tends to have a steeper learning curve.