Actually, hg sucks if you're collaborating with different people on different projects, because everyone has different hooks and extensions and so they insist on different workflows. On git everyone has compatible configs and the workflows mainly differ just in the number of long-running branches.
If you don't have issues, good for you. I'm not saying hg is unusable, particularly if you're using it within an organization or community that enforces a set of tools, workflows etc. But if you look at the github community where people tend to fork dozens of projects from a diverse set of people, that clearly isn't happening with hg, and I think the "Some assembly required" is part of the reason why. Git, on the other hand, is very much "Batteries included".
hg interface makes sense. there's clear distinction in semantics between commands and flags. that is not the case with git. git demands being a wizard to be excellent; hg doesn't.
hg repos typically are clones of each other: it takes work to not have all changesets replicated everywhere. the implication of that is that there's no forgetting branches; ergo, there's no confusion about what piece of the dag is pushed and what isn't. it's all pushed.
hg branches are 'true' branches, as opposed to refs. I could go into depth into how that plays out in better ways than git, but that's more of an actual essay.
hg extensions give hg more power - if you really want to get complicated, it's not unbelievably difficult.
hg project makes certain guarantees about stability of interface; tooling is easy to develop around that. tooling makes life better, often.
as a general rule of thumb, the hg project and experience adopts a principled way of choices; this flows out into the code and experience. it's a very clean and "better is better" way of working.
(For fairness, if you want the arguments in favor of git, try this: http://blogs.atlassian.com/2012/03/git-vs-mercurial-why-git/ . But honestly, I prefer Mercurial. It doesn't matter, because the vast majority of the people I collaborate with are using Git, but if I could make the choice, I would use Mercurial.)
But hg roxx. :-)