The best replacement for xfce is gnome.

The best alternatives to xfce are rated as following:
★★★★★  gnome
★★★★  lxde
★★★★  kde
★★  fluxbox
★★  openbox
★★  mate
★★  cinnamon
★★  unity
★  enlightenment
★  xubuntu
★  lxde lighter
★  xubuntu-desktop
  lxde faster
  e17
  gnome 3
  icewm
  lubuntu
  kde performance
  lxde desktop

Your alternative for xfce is not listed? Suggest!
Speaking about xfce, one probably shouldn't forget about compiz.

Other search terms related to xfce and their ratings are:
★★★★★ compiz
★★★★ ubuntu
★★★ nautilus
★★★ kde
★★★ openbox
★★★ i3
★★★ xmonad
★★★ awesome
★★★ gdm
★★★ kwin
★★ thunar
★★ fluxbox
★ dwm
★ mutter
★ debian
★ metacity
★ compiz fusion
★ docky
★ xubuntu
You have in mind a companion for xfce and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of xfce in all years. Click on graph for more.
xfce
gnome
lxde