Both have pro's and cons. Some people feel like single people aren't happy and are depressed. Yet you may not be ready or are too busy with school or work. On the other hand relationships are hard a days to make it work and last and may be drama but you have someone you can trust and talk to every day.
Single. Relationships are so much work, leave that crap to when your nearly 30. 20's is about discovering yourself and your future, not about being tied down.