it depends ... do you want your quilting to really stand out? if you do then judge what is going to stand out the most..is it mostly white/yellow? use black...is the black more predominent? use the white...would you rather the quilting stitches blend in/not be as noticable? then use a neutral like medium gray. take your top with you to a fabric store and lay each color across it a couple feet and see what you like.