I'm a huge fan of granular, I've done some side by side testing of a few granular synths and effects and I'm sorry to say I do not recommend Quanta, it has a somewhat "bit reduced" lo fi quality to it that takes a way from its sonic capabilities. if you like lo-fi, you can alway bitreduce your sample or add a lofi effect after in the chain
my favorite granular synth has been Pigments, they really give you a lot of options, even allowing you to FM the grains, and other unique controls
mangle is good too, but don't ever expect support or updates
Rapid is another favorite, it doesn't have quite as good of a grain engine as pigments, but rapid allows you to stack significantly more voices, and has much better factory content
I'm a huge fan of granular effects as well, just picked up mgranularmb, so I can't say much on it
but Portal is incredible, portal has opened up new sound design dimensions for me
as well Silo is worth digging into, it is a bit different than portal, but also has allowed me to explore new sonic territories
I'm planning on exploring more granular tools myself, and these aren't the only ones I've used, just my favorites from my collection