I was converted to Ratpoison during beta testing, after using XMonad for a while before that. fredg, wmfs sounds really interesting!
When I don't want to use Ratpoison, xfce is nice. However on my own machine, I have ratpoison alongside Salix Openbox beta as my secondary WM. As Thenktor says, it is really very pleasant to use when set up like that
And I see that as the larger point - configuration. Once you get things set up the way you want it can feel far too comfortable to make a clean break. But a large part of that is the starting point offered by a given distro's default configuration, which may not show the WM to best advantage. It's quite easy to get put off on first acquaintance.
That can be particularly true of tiling WMs. There is often an assumption that you will be immediately able to configure it just how you want, so the defaults may be terrible. That was my problem with XMonad - I did ok with configurations copied from suggestions online, but never got to the point of understanding how it really works. I think you need to learn Haskell
The other thing has got to be hardware. I suspect I'd like KDE if my machine were fast enough for it, though I started out with Gnome and liked it well enough at the time even on slower machines than this one. It was still better than Windows ...
Finally, Xfce has thunar - a good graphical file manager is very important to the user experience and overall feel of a (non-tiling) WM.