It depends entirely on what you require.
"Unfortunately", Spine's runtimes support a lot of functionality that Unity Animation (Mecanim) simply doesn't support because it was built primarily as a rigged 3D character animation pipeline.
If you need simple character animation and blending, Mecanim works fantastically! If you want exact control, exact playback of what you can do in the Spine editor, and things like dynamic constraints, so on, I advise using the SkeletonAnimation route. Take a look at the Spine Extensions and Attributes for making integration with SkeletonAnimation and Spine data very easy.
ie:
[SpineAnimation]
[SpineAttachment]
[SpineSlot]
[SpineBone]
So on. These attributes can rapidly help you build a simple Inspector to deal with what would normally be handled by Mecanim.