I think the quality of the brushes has alot to do with how well it looks on ur skin and how natural. I've used both and always go back to Macs brushes or Smashbox
amynyc is right the quality makes a hudge difference. I just got Gosh Brushes of xmas and their amazing. Their really expensive but its really worth it.
I think it makes a difference yes. I have a set of Sephora brushes, but I'm currently reading up on other brands, since I'm looking to buy some new ones.