So, I use fl, and I've always seen people saying that you can do practically anything with harmor or sytrus if you know your way around it, but I mostly seen all these people do heavy sound design on these plugins, like dubstep, eletro and drum & bass. So, I would like to know if these vst's are also good with more light "dreamy" sound design, like porter robinson pads and leads for example, and if so, can anyone point me at some tutorials.

have a look at the vandalism sound banks, i think they have some for harmor

if not you can always try freshly squeezed for spire, massive, sylenth for dreamy sounds etc

I personally don't know Harmor very well, but I personally think Sytrus is pretty good for a certain kind of dreamy sound.

If you're familiar with that generic early 80's sound; the DX7 electric piano sounds and etc, Sytrus is quite good at replicating those kinds of sounds; it can even directly load in old DX7 SYSEX files if that's your thing.

From my personal experiences, the more I rely on Sytrus in a particular track, the more it starts to kind of sound like some chill stuff from the 1980's.