There are a number of metrics one could use to determine favorite songs. How often do you come back to it over the years? How many versions of it do you have? Despite the fact that you've got well over 3,000 songs on your phone, which are the ones that you deliberately seek out the most?
By any of those metrics, one song which is a completely different kind of electronic music than any that I've shown here on this blog yet, has to be one of my favorite songs of all time; "Acid Nightmare" by A*S*Y*S*. Along with the Pump Panel Reconstruction remix of New Order's "Confusion" I think this is some of the most iconic samples of acid that you can hear. Sampling a bit of the Nightmare on Elm Street soundtrack, the drop into a tortured 303 bass line from that is just freakin' incredible (at 3:10).
Some of the remixes out there make it somewhat less acid and more trance, but given that Kai Tracid was one of the original members of A*S*Y*S* and his nom de plume is made by jamming together the words trance and acid, that's perhaps not too surprising.
Anyway, like I said, this is a far cry from the kind of stuff that I normally post on this blog, but my electronic music tastes do tend to be somewhat esoteric. I like the purity of some techno, trance and other related genres, although they do tend sometimes to get monotonous over time. The later acid stuff, like A*S*Y*S* is really hard and intense, though—especially compared to early acid house like Dr. Phibes or Phuture.