I've been a user of GitHub for a long time now. Ever since I started my career in Ruby on Rails I've had a GitHub account.
I'm looking again at alternatives to GitHub mainly out of curiosity. There's been some improvements to GitHub over the last few years and new features are gradually coming out but there are other options out there.
I did move some private repos to BitBucket a few years ago, but due to the lack of any extra features I moved these repos back. BitBucket just didn't have anything of added value that would keep me using it.
I tried GitLab a few months ago but I didn't really give it a fair go. I spent a couple of weeks using but I didn't really dig into it too much. I created my account there again to give it a try. I've been using it now for a week and I've moved a number of private repos over from GitHub. The nice thing is that as well as my repo GitLab has moved over my issue list for each repo. Another thing I don't have to worry about moving it across.
It's still early days to make a final decision on this but I've been impressed with not only what GitLab does at the moment, but the pace in which they are releasing new features.
The best thing and worst thing about GitHub is its community size. A lot of developers use only GitHub for source code hosting and although some people might see this as a good thing, it's like saying that Facebook is the only social network platform out there. Yes, there are a lot of people using GitHub but there are alternatives to it and I'm always willing to explore the alternatives to any development tool that I use.
Once I've spent another few months using GitLab I'll probably have a final decision on where I'll be hosting the bulk of source code. I won't be closing down my GitHub account if I do decide to use GitLab for hosting my source code. I still need a GitHub account for client work, but that's all it will be used for.