I would suggest that you locate a good audio store, put aside an hour or so to listen and do a thorough audition on both before you buy. No reviews can be better than your ears (hearing), as reading a review will not be what you will be hearing in your own preference.
I bought the stepdance last week to compare with my RSA protector, which the protector was the keeper after I bought and tried pico slim, mustang, iqube, SR71A. Sold my Lisa III with some regrets quite some time ago due to some reason, but Lisa III is still one of the best amp (put aside the weight and the RCA cables required).
The Stepdance is really nice, and to my ears, it definitely beats the other top amps that I have heard, accept my protector (and Lisa III).
This is just my ears and no wars intended. Maybe the stepdance is not fully burnt-in, but the Protector provides more detailed and more quality bass to me, and the soundstage seems wider in balanced mode. I could hear even the clear breathing sound of the vocals in some of the female audiophile songs I have in my Hifiman HM801, but not so obvious from the Stepdance. It is more laid back than the protector. Bass is alot nicer from the protector than Stepdance to my ears (again it is my preference).
So I sold my stepdance the next day, just like I sold my pico slim the following day after comparing to my protector.
I guess there's no "best" amp for everyone, and it is the "most preferred" amp to your ears - which reviews will not be accurate until your ears tell you after hearing it.
Thus, to me, the RSA Protector is the top amp to my ears comparing to stepdance (probably 2nd best), and can't compare to my previously owned Lisa III as I could not do direct audition with.
Don't trust my ears on this, as you may have your own top amp, which may end up to be pico slim (which I find it totally inaccurate from the reviews) or other amps.
Good luck in your search!
Cheers,
Mark
P/S: I am not a good source of review as I don't possess super sensitive ears. Only have owned a few top amps so far to describe my preference (Lisa III, RSA Mustang, IQube, RSA SR71A Blackbird, Pico Slim, Corda Stepdance, RSA Protector)