I have used and trained clients on Gratz, Balanced Body, and Peak apparatus. For my personal workouts, I prefer Gratz. The apparatus provides challenging workouts true to the classical method. For teaching clients, Balanced Body is a versatile tool. Balanced Body apparatus offers innumerable modifications various spring tensions, foot bar adjustments and many accessories) to accommodate all special populations and individual needs.
Gratz equipment is very close to the original (I have been on Eve’s reformer before in Santa Fe at Core Dynamics that Joe made for her). Heavy springs don’t allow you to cheat and you get results quickly. Men do well on this equipment I find. I am also a fan of Basil. These options can be more pricey, but are excellent quality. I have also worked on Balanced Body, Peak and Stott. I was taught on Stott when I first began, however I would not purchase it for myself or if I had my own studio.