I always love to play with my cubes, but more often than not my mom tells me to stop playing because my cubes are quite noisy (I have an Alpha CC and an F3) so i thought "what if i buy the quietest cube out there?". But wich cube should i buy?

I am sorry to not really have an answer, but my wife hates me 'playing with my cubes' too.
Slow and accurate turning helps but it is slow.

One silent method that I Love is underwater cubing. I am working on solving as many in a row (1 breath) as I can.

I think the F2 is pretty silent. I have never used one but it's what I've heard.

Question (and possible new thread): If a puzzle is twisted in the woods - does it make a sound!

Sorry - working late at work and just had to post as that made my day!

I like my cubes smooth and silent. My favourite by feel and sound is my black zhanchi.
It is a bit modded. To make it silent, the most effecive thing was to fill some plasticine in every cubie. I guess the lubing made it more quiet also.
The smooth tiles from cubesmith do not really change the sound, but they feel better to the touch, epecially when sanded a bit with very fine sandpaper.
I replaced the metal washers with plastic washers shaped to prevent the springs touching the screws. That takes care of the springy sound that you can occasionaly hear in most cubes.

cannot seem to remember on what forum it was posted but the ghost hand 1 and 2's were the smoothest and quietest. apparently lock up a lot though

If you have a smartphone, you could use the rubik's app. I have it and it's pretty nice, it has the 2x2 thru 5x5. It might not be the best for improving your solve time or anything, but it's a fun way to kill time quietly while still cubing.

As for physical cubes, I just have the Dayan guhong, and i wouldn't call it a quiet cube.

yeah any ghost hand by far will do the trick