Both Slicehost and Linode are good but when compared with Linode, Slicehost was slightly costlier. I realized it after reading the comparison done by David. I bought an account in Linode for testing and was quite happy with it. But I was lazy to move all my sites, since it involved some work.
The recent announcement by Linode to give 33% additional disk space wooed me enough and I gave in. 🙂
Now I am getting some additional features with Linode but for less cost. 😉