I still use SoundKeys... even when I'm working in 3D... even with Cinema4D and with Mograph... I still find myself going back to SoundKeys and it's because of the visualization and the falloffs. If you're new to sound keyed animation I'll share an old, but successful technique with you.
In one second of animation you seldom have more than 30 samples (frames).
In one second of sound you will have nearly 44,100.
How do you decide what part of the sound makes the cut? Most folks try to put too much sound information into their animation and the result is an epileptic fit of itunes screensaver-ness. A lot of programs allow you to narrow your sound information by averaging the samples or narrowing the bands but it's hard to know how well you keyed everything *before* you start animating. One way to find out is to create soundmaps. Run your keys to black and white values and stick them side by side. If the movement of the black<->white value is visually readable it is more likely the final animation will read well. If it's too similar or too jumpy in b/w there's a high probability your final animation will be difficult to watch. I still do all this with SoundKeys in AE because it's much easier to smooth the wave, narrow the bands, and compare keys visually. Otherwise you'll be creating a lot of shakey blobs.
I'm hesitant to share this movie because it's so damn old and my cameras sucked so bad back then (you'll have to forgive me I'd only been animating for a few months), but it's a decent visual example
of a side by side soundmap and animation. This was back when I used soundmaps for everything and I would drive the animations with textures. That allows you to do some cool stuff like changing an objects animation by simply moving or rotating the flat mapped texture projection. These days I actually pull the keys into the timeline and run expressions because it's a million times faster, but I still create maps just for visual confirmation.
Take a look at this soundmap.
It's a good example of "soft errors" that reveal themselves during the soundmapping process. This was a layout I used after experimenting for awhile. If you cover the top half and just look at the bottom... it looks pretty well keyed. The attack and falloff of the triggers are diverse and complement each other, but if you look at the top half (which visualizes displacement rather than value) you can see they don't match all that perfectly with the audio. If I would have tried to use these keys with a texture I'd be ok, but if it were used with a sweep nurbs or something of the like, it would appear very loose. After seeing this in the map I went back and adjusted my soundkeys and exported a tighter one for production (which I can't seem to find, sorry).
The thing is, that the slightest little adjustments in the interpolation of the soundwave will show up in your animation. If you're serious and you want it *really* tight I would really suggest a method like this. Standard EQs are ok, but nothing beats a soundmap, IMO and they're damn easy to build in AE with SoundKeys.