I had the first two Tyros models. I've also had nearly all the PSRs, several Ketrons, including the Audya and the latest SD7, six Rolands and four Technics. And one Casio.
I have a close friend with a Tyros 5 and have played it a lot. I prefer the Korg for many reasons, almost all of which I've listed several times in the past. After seeing and hearing my Korg, and realizing all the amazing real-time controls it has, my friend sold his T5 and bought a PA4X.
Don't get me wrong, the Tyros line sounds great and has a plethora of styles. I consider controls, weight, size, vocal processor, harmonizer all extremely important. Plus I love the new sound engine on the 4X, and I have all the styles I need and many, many more. I also love the touch screen, which is now adjustable on all models of the 4X.
It doesn't matter to me what model anyone else uses, I'm just relaying my own impressions.