Because the other two "flagship" windows phone 8's I have had, the 8X and 920 have given me problems regarding mainly the hardware. I had rattles from inside my 920, build quality issues and it started lagging?! I know, you never here those two words in the same sentence - lagging and windows phone. HTC I had problems with performance issues, if I were to have put my 3.2 GB worth of music on it the performance was reduced and the sim card reader started playing up, and I had further build quality problems with the 8X regarding creaking body.
So the Ativ S was my only real option left, I was sceptical about Samsung as I always remembered them to be really cheaply made and prone to scratching easy, plus there is the dreadful support they are giving windows phone at the moment, however it is the best windows phone I have ever had. The display is stunning, the best out there I recon, it has the size and clarity that stands out. The design of the phone is delicious, it is somehow faster than the other two I had despite there being the same CPU inside it. Lastly it was the cost, the Ativ S is the cheapest out of the 8X and 920, here in the UK anyways. I hope Samsung continues to make WP at this standard, Im sure if they put even half the effort in promoting windows phone it would steal sales away from the S3 and S4.