Welcome to the forum and congratulations on your nookcolor. Almost everyone here LOVES this device! Most of us have "rooted" it for more capabilites, but it's a great gadget as is, great for reading, surfing the web, listening to music and watching videos.
I have the Leather Writer cover (
http://gifts.barnesandnoble.com/Leat...?cds2Pid=35616), which I'm totally happy with.
It has some similarities to all the covers on your list, including the recess for the speaker, and the clip system for holding the nookcolor in place. I prefer this clip system to the types with elastic or straps. I also like leather over fabric, which your second and third choice also have. It looks like you prefer a brighter color cover than the Leather Writer. I'm not a fan of the "nook n" on the cover of the second book, but that's just me.
I would vote for your choice 3 for the aforementioned reasons.