there's no such thing as good free samples but you can find good vsts and the such though, but there's a lot of garbage out there.
some I use:
dblue glitch (search on google, creates glitchy beats, awesome for progressive house, electro and the like)
and if you are looking for quality material at a very affordable price, buy Computer music mag, lots of awesome vsti, be them analogue, additive or wavetable, they prolly have it, I especially like wusikstationCM, the mag also comes with lots of samples. good material to great loops most of the time.
and kita, it is wrong to think that 3xosc is as powerful as z3ta+
, you can make cool sounds with it, but its antialiasing up in the high notes is just awful, and you gotta have a lot of processors(effects) to make it sound good
