Looking for a good developmental toy for my niece

I need to find the perfect developmental toy for my niece. Her mom (my older siter) is a pediatrician so the pressure is on. I went to Babies R' Us and was overwhelmed by all of the options so I thought I'd hear from the experts -- you. Should I go with Lamaze, Baby Einstein, Leap Frog, Sassy....they all look the same to a novice. Which one would you recommend? Lamaze seemed to have some really cute soft books, but I'm just not sure. By the way, by niece is going to be 6 months and is already in to music and loves to hear her mom read to her. Thanks for your ideas!