I would take a window row (not the middle row), especially as you are traveling with a companion. There is a large and convenient storage space between the seat and window.

The con of the mini cabin is that it is in the back, and you hence leave the plane later. In addition, the foward lavs are slightly larger. But, all in all, there is not much difference, and I personally do not care much where I sit in the LH C cabin on the a388.