I've recently purchased Revlon One Step Style Booster, it might be the best money I have spent hair styling wise.
Initially I had purchased the One Step Volumizer but I was very underwhelmed. The brush is massive, quite loud and it barely does anything, at least that was my experience from one try, so it was returned. The Style Booster is so good. I have long, thick, straight hair with a slight wave, so the frizz is real after each shower. This really gives a salon blowdry. And I can't ever work a round brush on its own, so I was shocked that I could use this with little to no blowdrying dexterity. As the poster child of 'cannot be bothered' I'd highly recommend.