I like the first episode of the memory loss arc. Probably somewhat because of the refreshing new OP atmosphere brought about by Gerusama/new drawing/animation/whatever style, but it's interesting to see what the characters have to say. I guess up until the point where everyone figures out what's going on is the point that it turns into sterile filler.
I didn't even know what filler was really until the middle of Skypeia. I even went on to Gerusama's subs not knowing what filler was, actually thinking memory loss had to do with the real story somehow. Maybe another reason why I think the first episode of the memory loss filler is the best. Though when most of the fillers came and passed without me knowing I was just like, "well I guess it's time for the author to wind down again!" Little did I know that the author doesn't wind down using such methods…
Doesn't it take more effort to make fillers since there's no scenery, ideas, etc., from the manga? Must still be good money, but what do I know.