As someone who lived through that era and has owned maybe 30 MD portables, my perspective is a little different.
I've owned the Sony MZ-E10 (the thin one). Not only was it very vulnerable, it also obviously had some sort of digital-to-analog artifact coming from the digital amplifier that was less of an issue with the Sharp DS8/DR7/DR80. IMO Sony would not hit their stride in digital amps until the MZ-NH1 -- that "HD" digital amp was a lot more refined.
Having heard all the digital amps in modern DAPs and smartphones, I just cannot say for sure that these old portables will beat anything hands down. There's a part of me that's always got a question mark on the possibility of those "artifacts" I mentioned. I willingly acknowledge that my memory could be very bad, but this is the dominant memory of those early digital amps for me...
The non-recording players may be more sacrifice than they're worth, especially from today's POV where even the smallest, niftiest model is not all that compact at all. Not when we've got the ipod shuffle! If you have a practical reason to want a separate unit for playback, I'd get a recorder for that purpose too. Better user interface that should in most cases allow you to forego the remote.
If you go back further in time to tank-like portables from the mid-90s, they might have very good D/A conversion or very good amp, but those advantages were meant to cover for the subpar ATRAC codec at the time. Until around 1999-2000, many MD equipments risked not having quite enough computing power to properly decode ATRAC as intended, which is why we needed to worry about ATRAC chip versions at the time. This pretty much went away after 2001,02.
The portables I find truly memorable and would want to experience again today are the Sharp MT831 (or get its Kenwood clone L7R, for a darker tone)... I'd pick the NH1 or RH1 from the Sony camp, or the R909 for an earlier model.
If I must name a non-recording player, the Panasonic MJ99 is very pretty in jet black, but sound is meh and ergonomics is as crazy as one of those real housewives reunion shows. I love the Panasonic house sound but it's no wonder why they could not sustain their portable audio business.