To be honest they all have their pro's and cons for client and therapist.
Where do most people store their tension? A chair or stool massage is perfect for the neck, scalp and upper back area over a couch.
Stools although the best for moving about and cheap to buy, they are the easiest for clients with mobility issues, those who can't get onto the chair or find it hard to lie down.
Chairs and couches win on every other point.
So although companies may prefer to supply them they do not benefit the therapist or client. Stools aren't as comfortable and usually lower down so more of a stress on the therapists backs and legs. In a salon environment, they have no benefit over a chair.
On a chair, we can do most of the work with the clients clothes on saving time before and after treatment.
Although oil and tissues might not cost much we do save a few pennies by not having to use oil and the line of couch roll.
Chairs take up less space over a couch, lighter and therefore more mobile, they support the clients weight over a stool. For the therapists moving a client about on a chair is nicer over a couch, when we lift or move a client they are taking some of their own weight so the therapist has less of the 'dead weight' to move. From the therapists posture view, a chair is great when working on the upper back and head but we do have to bend for the arms and lower back.
Pain and 'issues' tend to 'zig zag' up the body so a lying down massage means we can investigate if there is another source for any problems. 9/10 times there is something 'off' in the hip area.
The client can usually relax and 'switch off' more lying down, we can also have support cushions so the client has the best comfort and warmth.
It is the only type where we can easily massage the legs and much easier to work on the lower back and hips.
The longer the massage the warmer we can get the muscles before we start tackling any problem areas, the client can spend much longer on the couch than a chair without the legs going numb.
For the best of both worlds, alternate between chair and couch.
Companies = Stools will gain the most money
Mobile/group events, upper back issues = Chairs
Relaxing outcome, lower body issues = Couch