What kind of tent should I get?

Okay, so I want to invest in a new tent this summer, but I can not decide on whether to get a small single person backpacking tent or a larger 2–3 person backpacking tent. My experienced friend suggested the bigger tent, because you can leave your stuff in them overnight or have someone else sleep in it with you.

I just wanted another opinion on this. What is best for casual backpacking, and some regular camping?

Thank for the help