Treading water, once and for all, can someone solve this for me?

I apologize for having three active threads. This is the last one. I promise. =) I'm *REALLY* confused about treading water. I've seen all the videos. I understand what sculling is. I've tried numerous things in the water. I've heard all kinds of conflicting information. As I understand it, there are various kinds of kicks you can use to varying degrees of efficiency including: - an 'upright' breastroke kick - a scissor kick - a bicycle kick - a 'frog' kick? - an egg-beater kick I don't fully understand the difference between all these kicks nor do I know which one is most efficient. What I do know is that I'm so frustrated with treading water, *I don't care* which one I learn. I just want to be able to stay upright in the deep end without assistance. I asked my instructor if I could just try a scissor kick, and she said "no, it's most definitely not a scissor kick, it's a a bicycle kick" -- implying, I suppose, up and down motion of the legs like you would have on a bike. But I've watched TI and GoSwim videos all of which show people successfully treading with a scissor kick. And if I understand correctly, a scissor kick is what I would do normally on backstroke or freestyle. So... is there any reason in the world that I shouldn't just stick with the scissor kick and hand-sculling for treading water? I need to pick one thing and focus on it, because I'm haphazardly trying all these different kicks and getting nowhere fast. Thanks.