depends, eink is wonderful, looks like a printed page, great for outdoor reading.
nook color is an LCD going from a Cruz to a nook color would be like going from an Emerson HDTV to Samsung HDTV , you'll notice the difference in almost every aspect.
nook color is great they both are for different reason.
If you can afford it why not have both
but if you have to choose one or the other, you are going to have to consider a couple of things, this in NOT an iPad, it does offer web browsing, which is great, it runs some minor apps, but this is an ereader first and formost.
There is more ereading functionality and features on the color and reading magazines are great and such.
it's tough if you had to choose one or the other.
I love them both.