I had been using the babyliss extreme air with a Wahl comb attachment (purchased separately). It got my hair straight on medium heat, on highpower. I make sure I dry my ends first, which ensures root to tip staight hair. It dries very fast. Only downside is that it's kind of loud and a bit heavy.
However, the Babyliss is not as loud as my new love, the RevAir! I use it on medium heat to dry and follow with a few seconds on high heat, then seal with cold for a few seconds. My hair ends up straight and soft. I find it easier to use to dry my crown and back areas compared to using a conventional dryer with comb attachment. I also love it when I open the filter after drying and find out I only lost like 10 hairs during the whole process.
I love, love, love the RevAir!