The MAC 217 is my favorite eye brush of all time. It blends like no other and makes it a cinch to get that perfect smoky eye. It's also engineered in a way that seems to be very hard to duplicate as proven by many failed attempts by other companies. I have three 217-type brushes: the Mac (of course), Coastal Scents, and Sigma. What sets the MAC 217 apart from others is 2 things: its fluffy yet stiff-enough bristles that allows the brush to keep it's structure in order to blend/apply precisely, and its tapered head yet flat top that allows you to apply color and blend at the same time. The Coastal Scents version isn't dense enough to keep it's structure and the Sigma doesn't have as flat a top. Most other companies don't even try an attempt at the brush at all.
So I'm very interested in this new Sephora Brush that looks suspiciously similar. It's called the Sephora Pro Oval Blending Brush #27 and it's made from natural goat hair, just like the 217. Sephora Pro Brushes are typically of high quality, so this could be a worthy competitor. Price-wise there's not much difference with Sephora being $20 and the MAC being $22.50, but I am curious if another company finally got it right, or if companies should just leave the heavy lifting for MAC after all.