I have been using xmonad for almost three years. The dynamic window layout management helped me to not think about positioning the windows. However, this is the same reason why I am trying out i3 as a trial. The absence of layout algorithms, and managing columns and using different layouts per column is appealing.
This means that I can run the browser in one column. In the other column I can run my editor, my debug window and log file in stacked mode. Or I can have two browser windows tiled in the browser column, and the terminals stacked in the other. I am sure this can be done in xmonad, but i3 makes it easy to achieve this.
There are some differences, but they can be ironed out with the configuration at our finger tips. I am going to give i3 an honest try, without trying to make it behave like xmonad, and see if it works for me better than xmonad.