I looked into both as a way of getting some tailwheel time. Basically Parachute dropping requires at least 700 hours and MEP. Glider tugging you need a C badge glider pilots qualification and being in the right place at the right time, usually as a member of a club who does it to help rather than getting paid for it. Many glider clubs have a list of people wanting to step into the tow seat already and many with tailwheel experience. Banner towing seems easier in terms of the hours etc you need to be able to do it, its just harder to find someone needing a pilot, especially a low hours one who doesnt have a CPL. Good Luck.