Both LXDE and Xfce are fast and easy to use. The desktops they produce are uncluttered and efficient. That said, I find that Xfce is a bit more pleasant for me to use due to its additional special effects and fewer design quirks. That is where the LXQt difference comes into play. The additional tweaking that the QT settings panel brings to LXDE seems to close the LXDE and Xfce gap considerably.