I ordered a GS3 at full price so that I wouldn't be tied to a contract. Also, I wanted to HSPA+ variant instead of the LTE AT&T version. Data speeds aren't a huge deal for me as I am in pretty fast wifi all day.
My phone tech path was iPhone 3GS, HTC Inspire, iPhone 4, HTC OneX, iPhone 4S and then the Galaxy S3. I buy unlocked so I can move around...That said, I prefer Android. I have fun with Android, but the Inspire wasn't getting ICS, and my HOX had some wifi issues that went unresolved even after adjusting the settings to the 2.4gHz band and then the random reboots didn't help either. I ended up with the 4S due to the fact that the GS3 wasn't announced yet and I still had some useful apps in that ecosystem. A few folks in the office have gotten their S3's and have been really happy with them. I popped in my sim and had no problems as well as enjoyed the excellent call quality. I really wanted to knock it's build quality given the HOX's unibody construction, but once the backplate is secured it feels very solid and sturdy. I could push down and flex the polycarbonate unibody on the back of the HOX reasonably easily but it was a gorgeous phone. Fantastic display, and though the GS3 has a great display, it's just not quite as good.
In what I have played with I thought Touchwiz was more stable than Sense. The multitasking issue was a hassle and the random reboots were odd. Then I would see amazing battery life one day and awful the next with the same usage. I thought it was a bad device so when I took it back and swapped it, I was a little bummed that the replacement had the same issues, albeit not as frequent. In any case, Touchwiz isn't as pretty but is more reliable, and I'll likely install the Apex launcher. Nice, clean, and very functional.