log4j1 was the beginning. Then one of the team left and build logback. The log4j2 team wants a logging framework which is build in "the apache way" and under "apache license". The project has grown fantastically and you can expect some cool features in future.

Still logback is a great framework. The log4j2 team learned of it and I think it is also in the other direction.

My (personal) recommendation is you use slf4j and chose a logging framework to your taste. You might choose based on a specific feature, on issue which has not been resolved in the other framework, on the license or how easily you can contribute.

That said, the log4j2 project is pretty active.