I used to be a huge fan of Visual Basic. When Visual Basic .NET arrived it seemed as most logical thing to use it instead of newfangled C#. However, it became clear quite quickly that Visual Basic is second-class citizen in that universe. Outside of a few exceptions, C# would get everything first. Whether it is a new feature or support for a new platform, Visual Basic would lag behind. So I switched and I haven't looked back.
Reason why I tell this story is because I am doing similar switch again. I love Mercurial. It is a beautiful distributed versioning system which hides all complexity from a user whether it is in a command line or a great GUI client. It is modern, smart, and well designed system. Any fault with it is just nitpicking and more than outweighed by its features. All that said, Mercurial is also a second-class citizen.
Other distributed source control system almost everybody has heard of is Git. It is powerful and it has reasonable command line interface (although that wasn't always the case). What it doesn't have is proper GUI support nor it is equally well designed as Mercurial - especially when it comes to multiplatform support. Git is a bunch of different tools and it shows (you can make a hobby out of finding different commands that do exactly the same thing). However, fact is that you can get used to its shortcomings.
Community gathering around Git is much bigger than anything Mercurial can offer. Small part of it is due to its undeniable power. But I believe big part is due to being Linus' baby. That gave it an early boost and, once you get used to its peculiarities, there is simply no reason to go to the other versioning system. And more people brings even more people in. And gets more people working on development. So peculiarities became bugs and get fixed. And platform liveliness brings even more people and better. Positive reinforcement at its best.
Simple search for Git vs Mercurial hosting or Git vs Mercurial push best illustrates the difference in usage. Git has simply won. Mind you, that doesn't mean that Mercurial is going to die - I surely hope not. But it is going to be always an alternative choice.
All that said, I will be moving my open source project to GitHub. Private projects I don't intend to share will stay with BitBucket but I will be switching them to Git as I do updates. Only things staying on Mercurial will be projects I am sharing with others and those I don't update at all.
And time with Mercurial wasn't really wasted - far from it. I would go as far to tell that it is the best distributed version control for taking the first steps. Pretty much all things I've learned can transfer directly to Git.