[FourzeMaru]

For best I'm going with Gokaiger for now. (Though I feel like Kakuranger might over take it as my favorite.)

As for least favorite I don't really have one.....yet. There's definitely some (like Goseiger) that I don't like as much, but I wouldn't go as far as to say I hate it. (Personally I found it kinda boring). The only series that I think might be my least favorite is Ninninger, though that show hasn't finished yet so I'll give a bit more time.