Bazaar is basically unmaintained at this point. If you look on Launchpad, the trunk branch hasn't seen a commit since December 2014 [0]. There hasn't been a release since August 2013 [1].
Mercurial is very actively developed, with dozens of patches a month [2]. They also keep to a planned rolling release cycle [3] along with deep commitments about backward and forward compatibility [4].
New features like the experimental evolve extension [5] are also really cool. I use it for day-to-day work and find it incredibly useful for editing work-in-progress commits into nice self-contained patches.
Mercurial is very actively developed, with dozens of patches a month [2]. They also keep to a planned rolling release cycle [3] along with deep commitments about backward and forward compatibility [4].
New features like the experimental evolve extension [5] are also really cool. I use it for day-to-day work and find it incredibly useful for editing work-in-progress commits into nice self-contained patches.
[0] https://code.launchpad.net/bzr/trunk
[1] https://launchpad.net/bzr/
[2] http://selenic.com/pipermail/mercurial-devel/2015-March/thre...
[3] http://mercurial.selenic.com/wiki/WhatsNew
[4] http://mercurial.selenic.com/wiki/CompatibilityRules
[5] http://mercurial.selenic.com/wiki/ChangesetEvolution