I'm upgrading most of my glass and adding a FF body, and the time has come for me to choose a 50mm prime (I have a 50/1.8, and I'm sick of its so-so bokeh and terrible low light AF performance, not to mention its s**t build quality). I'm torn between the Canon EF 50/1.4, which I've used extensively on loan from my brother-in-law, and the Sigma 50/1.4. I can get $75 (CAN) off the cost of the Sigma until Jan 31. I recognize the Sigma costs a lot more than the Canon, but I'm making these purchases for the long haul, and so price is not a factor; I will pay the money for the Sigma if I have to. Virtually every review of the Sigma I've seen says it produces far better IQ than the Canon, with particularly good sharpness at f/1.4 and excellent bokeh. The main problem with the Sigma seems to be the AF performance; some copies appear to front-focus, especially on close subjects at f/1.4. I'm a bit torn at this point. I'm willing to pay for the better IQ of the Sigma, but the widely-reported AF issues have me spooked. Anyone have any first hand experience with the Sigma?