I, too, struggle with these questions. I am seriously looking into buying a steam floor cleaner, as many of the floors I clean are tile of one kind or another. They are not cheap!
In residential homes, I currently use a fairly old fashioned method, but it works great. Vacuum first, of course. I use a Swiffer mop but do NOT use their icky wet pads. I use ordinary white washcloths, and I only use good, "safe" cleaning agents, such as Watkins or an H2O2 general purpose cleaner. I mop a small area and when the cloth stays white, it is clean. The reason I do this is because using a different sort of mop and a bucket, all you are doing is swishing dirty water all over the floor. I always have a Magic Eraser handy, for stubborn stains.
This works fine in most homes, but I am thinking about a steam cleaner because it would save time and energy.
I dont do any commercial cleaning right now. Just homes, and some of them are pretty large! For some reasons, most of my customers vastly prefer cleaning agents that SMELL nice. And yes, they cost more, but you dilute them, so over time it is not that pricey. It is worth the small extra expense, if it makes my customers happy.