Living in dormitory is a very good opportunity for the students to be socialized and make friends. I prefer to spend my time to have fun with my friends rather than to find out my roommate's personality. Also I have some strange habits that a few people can tolerate, so I would prefer to choose my roommate by my own.
I really prefer to live with somebody who I know. I do not like to spend time and energy to get familiar with each other's lifestyle and habits to see whether we can go along with each other or not. Take myself as an example. When I first entered university I did not know anyone so, I chose my roommate based on the university's preference. She was a very kind and calm girl, but her laziness caused many problems between us; and these conflictions prevented us to make a friendly relation.
Also, I think it would be fun to live with your friends. I am really an energic and talkative person, and I enjoy spending time with my friends. During my university days, I was engineering students and my lessons were really hard, but when I just find even an hour free, I used to go out for dinner or go to park with my friends. For example I remember at the weekends we used to listen to music, dance, play card and talk until dawn
Finally, I have some strange habits that some people cannot tolerate and my roommate should be too patient to go along with them. For instance, if even a friend of mine speaks or laughs during my studies for exams,, it would make me angry. I remember the night that I had a hard exam, and all my 3 roommates left room, in order to provide silent place for me to study for my exam.
In conclusion, I think it is better for students to choose their roommates because they are going to spend their whole time with them. So they should be people who they can go along well, and have fun.