I bought a T61p Thinkpad in 2007, and it's still my everyday machine. I've upgraded the memory to 8GB, hard disk, replaced a keyboard, and the battery, all very economically when the prices of those components came down. I love this machine, especially its keyboard, and am loathe to give it up unless I can find another with the same layout. In particular the pgup/pgdn/home/end keys are layed out in a manner which makes them very useful and natural for navigating within a window. I wish laptop chassis were standardized enough that you could customize these sorts of components easily so you can get just exactly what you want.
I'm thinking about finally upgrading sometime in the next year, but am in no hurry. I'm considering a Thinkpad T530 or a 15" MacBook Pro with Retina display. I looked at the Razer Blade Pro, but I didn't think I'd like the keyboard, and had concerns about durability (due to lack of data on that aspect and not having seen one in person to gauge how sturdy they are).