It depends on what you mean by "best." It is certainly a great program for mid- and bottom-tier pax who want free upgrades. To those (such as myself) who believe that an upgrade should require some payment (be it money, certificates, miles or the old 500 MSUs), not so much. I would prefer it if there were some discrimination between those to whom an upgrade is worth "paying" a nominal amount for, and those who will gladly take it but only if it is free. Flame away ...