there are many threads on this if you search that will probably be more useful than this response. but, hey do either. whichever you are used to. i live with one of my good friends (from undergrad) who isn't in med school with me and it's worked out (although i feel like we get on each other's nerves more now we are so out-of -sync in schedules). i have classmates who live alone and love it. i have classmates who live with other classmates and love it. i have classmates who live with other classmates and hate it. so different results basically. i would advise that before you settle down with a stranger, maybe ask all interested people about their hobbies/ study habits/ quirks etc and expose yours too. and don't wait til the last minute or you might get the roomie that everyone else tossed aside.
If you can live with other people, that is that you can come up with mutual rules of how to manage things in the apartement such as cleaning the place etc. without being an *** or a pushover then yes, you should live with someone else.
But if you're the kind of person who can't do this, loves living in solitude, or alternatively steals your roommates food when you're out, then please, for Pete's sake, live alone. You'll spare yourself and your roomate a lot of hassle.
I currently live alone after having two terrible years in undergrad with horrible roommates. At first I gloried in the aloneness: not having to clean up others' messes (and fruitfly infestations), lots of quiet, all the space to myself, no one waking me up all night playing computer games, no one stealing my food, no ones' pets being annoying. Lately, for a few months, I've been lonely and feeling socially isolated, possibly because it's winter and I don't want to drive places as much, so I have made plans to share an apartment with a classmate whom I often study with and think I know well. Time will tell whether my reborn optimism is foolish.
I was very selective about roomates before I got married. Bad roomates can make your life a living hell and that would not be conducive to learning insane amounts of material in med school. My buddy has a bad roomate. He hates going home and he is always tired because said roomate keeps him awake at night. I would live alone until you can find someone that you know well and could trust.