Rated 5 out of 5 stars

Translation add-ons: you find lots of them, and most of them are simple, going straight to the subject. It's the features that make a difference. So establish your "requisites" and search for them.
For my taste, Google Translator has everything I need and been searching for:
- a quick translation panel activated by shortcut (toolbar button too, but I'm more of a keyb man)
- text-to-speech WITHOUT handling the function to a Google Translator tab (or I could do it myself with a few keystrokes)
- translation popup when selecting text
That's pretty much for me. Of course, I loved the feature of doing in-page translations of some other add-on (can't remember which one), but it became a feature I rarely used.
Google Translator: light, rich, and straight to the point. Thanks a LOT, Andy - as always!