Yea, there is a trade-off between speed and accuracy. PrintWhatYouLike aims more for accuracy- you can reformat the page exactly as you want, but its more complicated to use and takes a bit longer. Readability is fast, but you have no control over the output.

If all you want is to select text, and then remove everything else, check out Nuke Anything Enhanced: https://addons.mozilla.org/en-US/firefox/addon/951