I disagree, the physical seat space of premium economy is remarkably consistent across carriers. You get like 38-40” of pitch, some type of footrest, and maybe 18-19” of width, plus additional separation between seats with thicker armrests with a small cocktail table. I think the only outlier is Air France with it’s fixed shell seat. Now, padding, the shape of the seat, accessability to power/IFE can vary, although some of that can be highly subjective.
I disagree that some are just Economy plus and others business minus, when business is almost entirely flat beds these days. No one in PE will think they’re thisclose to being in a flat bed. JMHO.