99% of my hiking will be with trail runners. New Balance to be specific, only because they fit best.
I tried hiking in running sandals a couple of years, and decided (after sticks stabbing me, as well as rocks and cactus spines) to only bring sandals as 'spare tires'.
Boots however, have there place. If you ever hike across 'clear cut', you'll wish you had boots. Also in areas with brambles like 'wild rose' and brier. Trail runners simply won't cut it.
So, it all depends on where and what you are hiking. If I'm on trails (not creek beds, clear cut, etc), trail runners are the shoe.