M.M.
I don't have either, but I do use a Eureka steam mop that I love. It's very, very easy to use. It works well and it was affordable. I purchased mine for $67 no tax & free shipping at: http://www.amazon.com/Eureka-313A-Enviro-Hard-Surface-Ste...
I highly recommend it. However, if you have your heart set on either the Shark or Bissell then I recommend going to Amazon.com and reading the reviews for both so you can compare the pro's and cons.
Regardless of which model you choose I promise you will be happy with the steam cleaning results. It's so much easier than mopping and so nice not to need to use chemicals. I really wish I had discovered steam mops when my son was learning to crawl - would have really preferred that to regular mopping with the dirty water & chemicals! Good luck! :)