Suspension seatposts offer great riding comfort as they absorb many of the imperfections on the road/trail. However, using a suspension seatpost will raise the minimum seat height and may not work for riders that require the seat to be in its lowest position.
Dropper seatposts allow you to easily adjust your seat height while in the middle of a ride. This can be useful in all terrain riding when you may need to quickly lower your seat for descents or raise it for climbing.
SR Suntour NCX/Thudbuster ST raises the minimum seat height approximately 3 inches.
Thudbuster LT raises the minimum seat height approximately 6 inches.