Why are they so effective?

Entrance themes are so effective in so many ways. It's just music that plays while someone enters the ring. At least, on paper that's what it is. Themes get people out of their seats. A whole stadium can go from silent to 11 when some songs hit. Either with boos or cheers.

So what makes them effective?

Really, only certain people have "perfect" themes. In my mind, if the beginning insn't catchy, it sucks. The beginning is the attention grabber. The one that says "He's Here." In addition, the background has to be good too, with clean beats and excellent instrumentals. The singing, if any at all, can't be annoying. No one wants to hear Jillians voice on an entrance theme, so that never happened. . . O wait, it did, and killed millions.
Therefore, my main point was that I have compiled a list of the best entrance themes in the WWE. (No TNA, most of them don't have singing, it seems).

*Please keep in mind, this is opinionated. I based my lists off of beginnings, crowd reaction, and overall likeness.

Best:
10.) Kelly Kelly (Who doesn't like that "Holla Holla"????)
9.) The Hart Dynasty (No matter how much people deny it, I think everyone still thinks Bret's coming out; so the pop is HUGE)
8.) Drew McIntyre (It's so obnoxious, it's Awesome)
7.) Cody Rhodes (No one likes him, so having a loud Whoa at the start makes it that much sweeter)
6.) R-Truth (It's new, but I like it. Great base, good lyrics. Not gonna lie, I get excited when I hear it)
5.) The Miz (AWWWWWWWESSSSOME)
4.) Edge (Probably could be number one, but some songs fit the judging better)
3.) Nexus (One of the most hated factions of all time, and their song is like a big flag that waves in your face just to get a rise out of you. Epic)
2.) Randy Orton (I think everyone cheers, takes pictures, and sings along when he walks down the ramp)
1.) John Cena (Are you surprised? The bass is magnificent. The noise blows the roof off. It happens every night and Lawler/Cole are still amazed each time)

I know I can't please everybody. I picked 10 of the best in my mind, so criticize how ever you want. Tell me whose I missed, I know I missed a lot of possibilities, so. . . Meet the honorable mentions

CM Punk, Sheamus, Santino (Yea), Christian, Triple H, Kane, Undertaker.

Cue the arguements.