I'm an Arizona native and feel like I have to put in my two cents:
Overall, UA has a better academic reputation. For decades, ASU was considered a second rate school, but in recent years, it has grown tremendously (now one of the largest universities in the country) and its graduate school has a stellar reputation. I still think that UA is considered the better overall academic institution, but in terms of law schools, they're really about equal. I have friends at both ASU and UA law schools, and frankly, it's all about the same.
As someone who went to high school in AZ, I can definitely attest to the reputation of UA, but ASU is certainly gaining respect, and I would expect that in the near future, it will be the more prominent school in most respects. Their business school is excellent, the UG honors college is extremely good, and their collaboration with the Mayo Clinic brings a much needed medical school to Phoenix, and this addition seems to do quite a lot to improve the reputation of ASU's science offerings.
Personally, I'm probably going to go to ASU for law school, but that choice is based entirely off the availability of the dual degree program I'm looking for.
Particularly for someone who wants to practice in Arizona, there is really no difference. I have to agree with the consensus and say pick the city you like better. Phoenix is huge and has a wide variety of things to offer, but Tucson is really quite nice, despite its reputation as a dump. If you're into outdoor recreation like mountain biking, there is no better place in the country than Tucson.