The bus is the best option for those seeking convenience and availability. The downside is the lengthy travel time.
Traveling from Nan to Koh Samui involves a bus journey taking approximately 360 minutes. If convenience is what you're after, this option fits the bill. However, be prepared for the relatively long travel time.
The cheapest option is also the bus, with prices ranging from 450 to 900 THB. However, it requires a significant time investment.
For families, the bus offers a comfortable solution with spacious seating and availability throughout the day. Keep in mind the prolonged travel duration.