Ive used plasmas and theyre great, dont get me wrong, but a good torch is almost as good and alot more flexable.
You can weld, braze, heat and cut with a torch. Plasma is limited to cutting. Plus O/A is alot more portable, which is important if you want to do stuff outside the shop. ( Yes i know you could rig up a generator and a source of air, but thats not too convient)
Ive worked in a couple fab shops, and at least in my experience, Oxy/acet is still king both handheld and on cutting tables. But plasma is catching on.
Plasma gives a good cut, yes, but with experience you can do some amazing work with OA. Once you get the cut speeds , gas settings and tip height down you can have nice clean cuts with minimal dross. Some guys ive worked with could freehand OA almost as good as CNC plasma.
Any plasma cost savings in gas over OA are offset by the cost of the plasma unit itself, plasma consumables and extra air filtration required.
For most people, cutting steel, OA is fine. If you got the money, plasma is great, but for alot its overkill.