FF Origins is badass. I'm about two hours from completing FF2, and I finished FF1 a few months ago. Hopefully Square will release one more collection containing FF3 and Seiken Densetsu 3.
I never played the original, but I liked the Origins version just fine. I'm sure though, that if I had played the original, I'd be of the same opinion. The original graphical presentation has nostalgic attachment for some people. Hell, I'd have been pissed off if they had re-tooled FF4's graphics for FF Chronicles.