If we're going all the way back to GUILTY, I say Marionette was epic <3 Edit: Oops, forgot Together When...! Also epic <3 And in NEXT LEVEL...well, Days was cute...and Curtain call was pretty... and R'n'RC was cool, DLB was perfect, Microphone was full of symbolism and Ayu looked fierce, same with SLT, Yw... was full of symbolism, BALLAD was gorgeous and symbolic, MOON was full of symbolism and Ayu looked gorgeous (imo it wasn't boring XD), crossroad seems cool from what we have...
Imo, she hasn't really had a period of amazing-amazing-amazing-amazing PV's right after another~ She has a few amazing PV's here and there, some good ones sprinkled around, and some downright bad ones thrown in there~ I don't think there's an actual period of decline or amazingness (except for (m)u's PV's, but don't get me started on that
). (^_^)