Véronis compares Systran and Reverso, two popular automated translation tools.
In order to compare them, I take a sentence in English, have it translated in French, and then back. This has the benefit that even if you don’t read French, you can appreciate the quality of the tool.
I start with this sentence:
I gave John a piece of my mind.
Systran gives me:
J’ai donné à John par morceau de mon esprit.
I gave to John per piece of my spirit.
Whereas Reverso gives me
J’ai donné à John un morceau de mon avis(esprit).
I gave to John a piece of my opinion (spirit).
I think Reverso is better here. Note that most search engines out there use Systran.