Of course, which looks better comes strickly from personal tastes ... but to my eye, orange heads do look better over lighter sand with the leucosticta looking better over black sand. Daemons tend to look good no matter what, but I'd give the lighter sand a slight edge for them.
I'm sure they are fine day to day, and yours look very healthy and happy. Could be a problem for breeding but what's the chance of that anyway . It was also mentioned that lower pH brings out more color, but again yours looks great...
Figured I'd quote this from South American Eartheaters by Thomas Weidner for future reference.
Weidner said:
S. daemon is very much a warmth-loving cichlid which should not be kept at temperatures of less than 26C, and for which soft (<8dgH) and acid (pH 4.5-6.5 max.) water is a mandatory requirement for good health. If these parameters are exceeded long term then these cichlids may lose their colours and skin leasions will be inevitable.
Without reading too much into the information though (I tend not to on species I have no access too), I imagine they'd also do very well in a very dimly lit leaf littered tank with the resulting tannins not neutralised by products such as Purigen.