I don't understand why people here are even talking about Cena. But since you do, I'll make a quick recap of how I see him:
Cena is a guy with the potential to have an entertaining character, with an edge, and that is his "Rapper" gimmick. However, since he's Vince's good and loyal (yabba dabba).. company guy.. he supported his idea of going PG (I even remember reading somewhere he was the one that advised it to him, though this might be just a rumor), and became the face of the PG era. Since then, his character became a corny, self repeating "Super-Cena". God, this character of his is unwatchable by anybody over the (mental) age of 12, 13 at max. He sure has the potential to be interesting, entertaining and more or less realistic, but he'll never do it as long as Vince supports PG TV. The Rock made him up his game a bit to what it used to be, but once Rocky is gone, Cena is gonna go back to being the big fat bawl of fruity pebbles that he was ever since WWE went PG.
Now that I said everything I think about Cena here, time to switch to the topics which are actually relevant to this thread.
Miz looks horrible. Really? Really???
Well, the answer is - partially.
Lets start with realizing the situation the Miz is at - We have a verbal feud between SuperCena, who has the legacy of being a fucking unbeatable superstar in the last 6/5 years, and betwen The Rock, The Great One, The most electrifying man in ALLLL of ENTERTAINMENT... And the face of the company before Cena (along with Stone Cold). In the same time, Cena and Miz are having a physical championship feud.
Do you expect the Miz to look better than The Rock? In his first title reign?
Newsflash for you - at this "legendary" feud, the draw of each character is measured first and foremost by his legacy. The Rock has had numerous number of achievements, he's a solidified Superstar, and he has the reputation of a real Super-face. Same can be said about Cena, though his standing of "entertaining" is mainly with the children. That's why, as long as the above two do good enough promos, they'd get twice the pop as Miz would for promos of the same quality.
For example, the Miz had cut a pretty impressive and very intelligent promo this Raw, which might not have been filled with as much energy the Rock's, but surely was entertaining if you actually listened to the words. It conveyed a few messages and promises, that you people will probably look back at and remember before this this is over.
Than Cena came out, and cut one of his usual piece of CRAP promos. Hell, I actually think the one joke from Alex Raily was better than everything Cena said, combined.
And in the end - The Rock. Well, he certainly had the energy in his words, and was a little funny, but 70% of his pop were respect pops for him, The Rock, not his promo - since the promo was a pretty mediocure one, with only a few exciting spots, and some spots which just didn't flow with the rest of the promo. His triple "I bring it" crawd chant already starts to look a bit washed up - hope he doesn't do it again until there actually is some historic spot to use it in, or else it'd lose its "it".
Anyhow, out of the promos themselves, I'd actually have to give Miz the price for the best promo today. The only reason he looked weak is because, as I said before, The Rock and Cena have just too large legacies for someone as new to the main event as Miz to handle.
On the bright side for the Miz, I hope they let him have some real historic moment this Wrestlemania, which would solidify him as a new top heel in the company, like Orton was in his Age. Come on Vince, I'm counting on you to make this happen!