I was in the market for a small SUV, and I test drove both of these. I liked the Tucson a lot, but it is small. The Santa Fe is a nice size, and comes with a lot of nice standard features however the styling is goofy and will be redesigned for 2011.
The 2011 Sorento is out, and although very boring is a nice vehicle. I had one as a rental car for a business trip, and I liked the standard features like Steering wheel audio controls, Trip Computer, Sirius, Bluetooth and the USB port. It is Kia's version of the Santa Fe, built off of the same platform with many of the same features. It was a decent driver, but very boring and bland. Even with all of the standard features it had, I didn't want to keep it.
Might want to check out Equinox and Terrain. These two have a lot more features, are a nice size and are very well put together. They would be my first choice, followed by the Hyundai/Kia offerings. I really didn't see anything else that stood out to me.
Quality wise, I think all of the above are fine, well built vehicles. All have 100k warranties, the GMs have the excellent Ecotec 4 cyl engines, and optional V6s that are looking good also. My father has a 2007 Tucson, and loves it. He has about 60k miles on it, and the only problem he had was a seal that blew out on the A/C compressor. It was fixed under warranty without issue, and he was given a rental car.