I'm going to be a little unfair. If a game was multiplatform and there's no reason to believe the platform I played on was better, then I'll apply it to any of the consoles, likely where it was strongest if that applies. However, I will not split up a series I played on the same console into multiple ones just to fit them all in. I also have to have owned the console in the past.
With that said:
Xenoblade Chronicles (Wii): I've said a lot about this game elsewhere. Simply put, it is one of the greatest overall experiences I've ever had with a game, and while it isn't perfect, it does manage to nail what matters and delivers a fantastic experience on multiple levels.
Prince of Persia: The Sands of Time (PS2): Along with being a hallmark of video game storytelling, the gameplay was absolutely fantastic. By far one of the best platformers I've ever played mechanically, only losing out its sequels. However, what it lost to the sequels in terms of gameplay, it way more than made up for it in terms of its beautiful, albeit simple, narrative and storytelling structure.
Mass Effect 3 (Xbox 360): Really, I love the whole series. In retrospect, I probably had a lot more enjoyment with ME3 over the others, though. It simply did the best job of merging solid gameplay (something the first lacked) with a good story and atmosphere (something I felt the second lacked). It might have been very check-list like, but the overall feel and experience was the best, regardless of what happened in the last few minutes.
Civilization V (PC): I love the Civilization series, and it is easily one of my favorites. Among the ones I've played (Civ3, Civ4, and Civ5), I felt Civ5 delivered the best experience, even if it wasn't as deep as Civ4 (but that's not saying much). It fixed most of the major issues I had with the franchise up until that point (minus AI issues) and still retained a lot of what I loved.
Super Mario Sunshine (Gamecube): Loved the tropical atmosphere and level design of this game. It's easily the 3D Mario game I've spent the most time with, and it still remains the one I view most fondly.
