My favorite room on PS is definitely The Studio. I am a person that relies on music for so much, and I love being able to explore new artists, and also share my finds with people. Not to mention, the room is super chill, and I love the people there.
Other rooms I enjoy:
The Happy Place: I love helping others, and this room allows me to assist others that are across the world. It's a neat thing. I also love the room culture and people, not to mention this room is basically training for dealing with others in real life.
Cafe: I'm a foodie. Food and music are my current stress coping mechanisms, and I would still be a huge foodie if I found a better route for this goal.
Video Games: I'm into vidja games as well as the lame memes the room generates. I wish that I brought my wii u/3ds to college sometimes, but eh.
Writing: A place for writers to mingle, and I've used this room for my crazy ideas in playwriting. I should probably try and start writing some more creative pieces, but I'm lazy and such.
Game Corner: This room will always have a special place in my heart. I've made so many friends and have so many fond memories in this room. The community might be overwhelming at first, but it's one of the best you'll find on PS.