Good topic,
MEGA.NZ is usable with 3.7GB of ram its success depends a bit on the browser your using(even try configuring through about::conf and settings+addons)
I found personally. It also depends on how many programs in XP for instance you have in the background. I have had some fairly decent luck using serpent X86(roytam1) to download files in the browser using MEGA.nz(usually no more than a few GB's).
Now the piracy aspect is controversal, it is based in Auckland New Zealand so the regulations may be different which goes back to the possible reason for the point you made.
Plus I found that now the very generous free 50GB of storage with free accounts has passed. I created my account a long time ago, and someone told me very old MEGA accounts aren't affect, will have to check.
Personally like yandex disk, but one final question besides MEGA.nz which do you believe has the most security and privacy?
Have a great day or night,
-Saga