I dont understand why are you even making such poll. Ofc everybody prefer SDK over DLC. DLCs are crappy made, non balanced, overpriced, short and not worth it. With proper SDK the modders can create tons of maps/missions/new models/sound and texture packs and the maps will be balanced, everything (not just the maps) will be suggested by true fans of the franchise, everything will be free, it will not split up the community, the lifespan of the game will be continued literally with years. Its a no brainer when it comes to SDK or DLC. DLCs are made to make money, SDK made stuff is made by the heart and joy of the true dedicated fans.
EDIT: Oh and besides everything I mentioned I forgot the community balance patches. Just for that alone its worth to have SDK.