If you're speaking solely of a PS3, my answer would be the Blu-Ray player capability and the games that Sony does have exclusive to the system.
If you're speaking in a general sense, there have to be games that attract your attention in addition to giving you features you desire.
Towards the one post I saw earlier (cannot be bothered to thumb back through and link) speaking of console inferiority versus PC: Duh? Graphically consoles have always been a generation (at least) behind versus PC capability. Yet there have been many titles exclusive to individual consoles (or portable game systems) that haven't seen the light of day on a PC. It's also wondrous to watch the evolution of how far games progress on a given system. For example, think of early PS2 titles versus games that came out much later in the console's shelf-life, like God of War. Truly amazing stuff.
Consoles are so far behind now that it's absurd that they still exist. Even the Wii U at launch will be obsolete compared to even the average gaming PC that is already a couple of years old (basically, if you are running a desktop with an AMD 5850 or better graphics card and an i5 quad core, it's already better then the Wii U). Graphics hardware technology has advanced so much in the last several years and the fact that Sony and Microsoft didn't release consoles last year or even this year baffles me as they are hindering PC gaming from moving forward.
And Unreal Engine 3 won't be running without modifications on consoles, not unless they are super high end and comparable to a higher budget gaming rig today that is running a 7970 or GTX 680 for graphics, which I know Sony and Microsoft both won't attempt unless they want to go out of business.