As for me, I`m a big fan of listening to all kinds of music!
That's very good, openness to learning/enjoying different kinds of music, from different eras/genres/styles is a gift in my eyes, as you aren't quick to judge something until you give it proper time/listening..
like more rock and 90th music
Good choice! many great (rock, alt, punk, metal, Shoegaze, Triphop etc) acts emerged from that era, from RATM, GD, Nirvana, AiC, Pearl Jam, Soundgarden, MBV, Weezer, Faith No More, Portishead & many many others.. all great music, you really can't go wrong there.
But because of my studies, I can't enjoy the songs of my favorite artists so often
You can use the Pomodoro Technique
, it's 20~25min of studying then after it another 20~25min of doing something YOU like, in this case listening to music, then repeat over and over as much as you like.
You get more work done this way, as it's like giving yourself a reward for studying for 25min straight, and with much improved focus and without the risk of getting bored..