I have been asked MANY TIMES what bottle brush I use. I have been through several and found one that has NEVER disappointed me. It's Dr. Browns Bottle Brush.
This bottle brush has so many good features, where do I begin? Lots of bottle brushes have the sponge at the top, but since the top of the sponge in those bottles is flat, they do not reach the bottom of the bottle because of the metal that the sponge is stuck through. But Dr. Brown's sponge is slightly offset at the top, guaranteeing to get the bottom of the bottle.
Another great thing about this bottle brush is that the handle takes some effort to bend. Unlike, many of the other handles I have seen, this one does not flex as much when it is used vigorously.
Many other bottle brushes come with a separate nipple brush, but I just stick the sponge at the top of this one into the nipple, give it a twist, and I am good to go as far as cleanliness goes.
So, there we have it. Another recommendation for something available at my Amazon Store.