The best replacement for mercurial is git.

The best alternatives to mercurial are rated as following:
★★★★★  git
★★★  subversion
★★  svn
★★  f50
★★  bazaar
★★  hypervenom
★★  tiempo
★  tfs
★  adizero
★  perforce
★  ctr360
★  git 2013
★  t90
★  adidas f50
  git popularity
  github
  elastico
  hyper venom
  git branching
  nike hypervenom
  git windows
  adidas predator
  clearcase
  tortoisehg
  capricious
  total 90

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

Other search terms related to mercurial and their ratings are:
★★★★★ tortoisehg
★★★★ xcode
★★★★ tfs
You have in mind a companion for mercurial and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mercurial in all years. Click on graph for more.
mercurial
git
subversion