The best replacement for mate is cinnamon.

The best alternatives to mate are rated as following:
★★★★★  cinnamon
★★★★  green tea
★★★  xfce
★★★  kde
★★  date
★★  teammate
★  lxde
★  gnome
★  twin flame
★  cell mate
★  cairngorm
★  broil king
★  roommate
★  matcha
★  swiz
★  bissell flip it
★  otterbox
★  black tea
★  sole mate
★  international delight
★  guayusa
★  cinnamon faster
★  robotlegs
★  gnome fallback
★  soulmate
  boatswain
  gtunes
  cinnamon 16
  half and half
  life mate
  cinnamon desktop
  oolong tea

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

Other search terms related to mate and their ratings are:
★★★★★ compiz
★★★ losing your soul
★★★ ubuntu
★ loosing your soul
You have in mind a companion for mate and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mate in all years. Click on graph for more.
mate
cinnamon
green tea