Seating is one of the most important factors to consider because it applies to everyone who sets foot in your room. Comfortable seating is needed to create a room your peers will actually want to visit and spend time in.
Using your bed as a couch might be the comfiest and most convenient option. Beds are definitely long enough to seat multiple people. You wouldn’t have to pay for a couch but would still get the community that comes from friends sitting together. The only downfall about a bed doubling as a couch is that your bedspread and covers will get messed up and pushed around whenever people sit on them. Also, a low bed might take up more floor space than you are willing to give up in such a cramped space.
Futons are cheap and common in dorm rooms. They can be easily transported from home to college and can fit in the limited space of a dorm room. If you think futons are too small or uncomfortable, you can splurge and get an actual couch if you have a way to transport it to school and back.
A couch isn’t particularly always necessary for a dorm room since there is such limited space. Sometimes the best option is the have portable chairs. While chairs don’t bring together as many people as a couch would, they are perfectly cozy and sufficient. If you are like me and you move your room around a lot, it can sometimes be easier to come up with designs when there is not a couch to factor in.