Some English learning center teaches "Headway" (Oxford),
and some others uses "Interchange" (Cambridge) or "Side by Side" (Longman).
I have dicovered also more useful courses like "Face2Face" (Cambridge),
and "Berlitz English - Language for Life" this last one looks like a perfect course also,
but I think it's a specially for Berlitz language center brunches only.

Do you like one of them or other book series ?

So which book you prefer ?