I suggest starting with the subjective (looks) vs the objective (isolation). The LS50 is semi-high-end kit and as such isolation stands are vanity....IMO unless your particular needs are unusual any decent stand will do. Once you get past works well enough and functions as desired the only thing that matters is looks.
The LS50 is a unique & simple "soft" form, a lovely one at that...IMO any busy looking stand will be more attention grabbing than the speaker, which is kind of silly. Visually not unlike spinners on a late model Benz
. While tastefully designed I think the Concept 20 stand looks like a rocket ship at launch ready, just a bit too dramatic. The design approach of the SF 104 is to my eye the opposite of that of the LS50, and these opposites do not attract. The LS is a mini monitor and mini monitors can look great with a simple base and single unobtrusive upright. In concept similar to Sonos stand, except heavier all around. You could piece something nice together at a music store from a clean lined simple mic stand base & a half high mic stand pole, then add a mount at the top to rest/attach the speaker. That's what I had planned and hoped for my GX50s, however here in SA the simple 12” round mic base I favor is not stocked. If the height is critical, a machine shop can assist with pole modification, and you could have the finished stand color matched or what have you at an auto body shop. In my view way more attaractive than a look at me stand.