I grew up in San Antonio, and have been a Spurs fan my whole recollected life. I lived in Seattle from 2001 to 2007. I watched a lot of Sonics games because I enjoyed watching basketball and I, at the time, could not afford League Pass. I never rooted for the Sonics. It's not that I disliked them, but I already had a team, and my team was good.
I saw probably a 10 basketball games in Key Arena. I have seen two or three games at the new Spurs arena. As a fan, there is no contest. Key Arena is by far the better place to see a game. It's not even close. The Seattle venue is small, quaint even, and the worst seats in the house offer a decent view; you're never far from the action. I used to live within walking distance of the arena, and it is in an amazing location. You can take a 3 minute monorail ride to downtown, yet there's still ample street parking available. The area streets are safe and teaming with good restaurants serving all sorts of food. The arena itself is nestled in the Seattle Center, with plenty of wide open meeting spaces... you are in the middle of the city, but it's not cramped.
AT&T Center, or whatever it's called, is new. The upper deck seats feel like the upper deck. It's dropped between the Freeman Coliseum and a golf course. There's nothing within walking distance except for a chance for a good mugging.
The whole thing makes me sad. Key Arena, the supposed reason why the Sonics are Oklahoma City bound, is a wonderful place to be a fan. But it's a horrible place to be an owner. That's why Stern moved the team; so his rich friends could get richer. I realize I am just pointing out the obvious here. All I can do is be yet another voice declaring this whole affair was an affront and insult to the fans of Seattle and the fans of the NBA.