What's the best tool to find and replace regular expressions over multiple files?

sed -e "s/pattern/result/" <file list>

find <other find args> -exec sed -e "s/pattern/result/" "{}" ";"

for file in @filelist ; do
  perl -p -i -e "s/pattern/result/g" $file
done

for file in @filelist ; do
  cat $file | sed "s/pattern/result/" > /tmp/newfile
  mv /tmp/newfile $file
done

vim -c "argdo! s:foo:bar:gci" <list_of_files>

vim <list_of_files>

:bufdo! s:foo:bar:gci

sudo apt-get install regexxer