I tried a number of them when I first started looking, and a couple times since, but i3 seemed the easiest and most intuitive.

I've heard XMonad is fine once you get it configured, but configuration is a pain. i3 configuration is pretty easy. Binding a key looks like "bindsym $mod+Shift+Left move left" (move a window left) or "bindsym XF86MonBrightnessUp exec xbacklight -inc 10" (make laptop brightness keys work, by executing the xbacklight app). It ships with a good default config too, so you don't have to write everything from scratch.

i3 has decent (though not perfect) mouse support, something a lot of tiling WMs are lacking.

i3 uses a tree to store windows internally, which affects how they move. Moving windows around feels very natural to me.

For the uninitiated: windowing managers are just that, not desktop environments. Which means you can use a tiling WM within a DE like Gnome or Xfce, if you want. I actually used i3 within Xfce for a bit, then with only the Xfce menu bar, but I found I just didn't need them.