All I'm going to say is..Omnislash V5 into EX Mode. V5 is so ridiculous. He's got a great break game, yes, but..that's what makes him better than just Mid.
That Omnislash V5 is..dare I say it? Broken. I think that's just how Cloud was made to be played though.
They made him, "LOL EASY MODE" because he's a fan favorite, so even the noobs can get easy wins off of you as long as they have Omnislash V5. As for Sephy..he's got great range, but that's exactly why I think he would deserve to be higher than Bottom, at least. You can have some trouble with a good Sephiroth player because of this.
It's so hard to get in close to him and let's not forget that downward stab (lol Aeris killing move). I just think Cloud should be a little above Mid and Sephiroth should definitely be out of the Bottom Tier. Then again..this is just my opinion, just as the tier list was made from your opinion, so don't think too much about this, lol.