I like 8 and 12, they seem the most functional as a support pillar. the other ones seem a little too random or lacking purpose. that circle in the bottom of 8 would look great housing a spinning fan.
I like 1, 2, 8 and 12. remember that a pillar is suppose to be holding something in place, so they must at least look robust, their not only for beautification, a bit of sense into the environments, even sci-fi environments, are always welcome.
Thanks for your replies Mcejn and Sam. I decided to downsize them to 6 8 and 12, I will start sketching detailed versions of them and keep posting, hopefully that will keep everybody on their toes and not let this thread die :P I appreciate everybody's hard effort as always, thanks again!