The best thing about pre-rolled cones is that they're simple to use. Cones come ready to use, so your customers only need to grind the flower and fill them up. These are ideal for novices or anybody who wants to smoke but doesn't want to spend a long time learning a new technique or rolling the perfect joint.
Alternatively, if your customer base is more of smoking pros, rolling papers are a good choice. Rolling papers are not ideal for beginners because they aren't easy to use and can scatter herbs. However, people with enough experience enjoy rolling the perfect joint and puffing it up.