Equipment is made for the purpose of taxing the body based on different physiological, and musculoskeletal aspects. To have a one set of equipment be your favorite for your clients to use may be a disservice to your clients or patients. Each client should be unique in what phase or stage of adaptation their body is at to determine what exercise to select and what piece of resistance training equipment to use. I do agree certain commercial strength training pieces are better than others, however the importance is behind how to correctly sequence and progress with them relative your client/patients goals.
If I had to choose from the ‘machine world’ I would probably go with Freemotion. What I like about them is that they allow for more adaptation to different body frames and sizes. On the other hand, I also take machines with individual weights per side (as in Hammer Strength) over those with just one weight stack.
Having said all that, my favorite ‘machine’ is the floor with balls, bosus, rollers, bands and all the other gadgets.