Kraz's favourite toy has always been this little $6 quad-pod that I bought for him when he was a baby. He'd sit there all day doing nothing but spinning it around and around if I let him. I've tried a few times to replace it with something a little less cheap (and plastic) but he won't have that.
Aurélie's favourite is, hands down, her swing. She sways around, hangs upside down, chews up the beads, and entertains herself for hours with it. She's such a little monkey.
Rafi, unlike her siblings, isn't much into actual bird toys. Every so often she'll hang upside down and rattle them around, and she can be enticed to show interest by stuffing a toy full of almonds, but her favourite thing to play with, without question, is my big white mug. She's been in love with it ever since she came home, and I have to be careful about drinking from it while she's around, because it'll inevitably end up on its side, being rolled around the room.