I have experience with both Leer ad ARE..... Leer on an '08, and ARE on an '06. My opinion is that your choice should depend on what you're going to use it for.
I have a Leer 100XQ on my '08 super duty.... I chose Leer because I liked the looks better, I also liked the way the bottom edge of the Leer cap hung over the bed rail.
I think quality between the Leer and ARE are comparable. However, I think the ARE has more "substance" in the roof of the cap.
I have used a Yakima Roof Rack system on both trucks to carry canoes, bikes, lumber etc..... The ARE had much less flex than the Leer does.
I'm actually waiting for a call back from my Leer dealer regarding getting a front window replaced..... is spontaneously shattered the other week. Not sure why, there were no nicks or chips and I didn't hit it with anything
So, hands down, I like the looks and fit of the Leer better, but the ARE seemed a little beefier, so if you're going to be rough on it, take a close look at ARE.