I have no idea about the traffic flow ,, and want to know which one is the busiest one,, because when I log in, I want to control continuously,, not to worry about no traffic in the area. So, what do u think?
Anyway I am new in VATSIM, and just beginning with my training.
Welcome to VATSIM, and Welcome to VATUSA!
to directly answer your question, you will find this link helpful
http://stats.vatsim-germany.org/ Just have a look at the "Top 50 World Airports" Its not an official top 50, but its as close as you will find,
unfortunately due to the nature of VATSIM, you will never control continuously
As far as the best ARTCC, their is no way to tell what ARTCC is the best, but what we recommend is you View each ARTCC's website, you review their material, Ask any questions to the ARTCC Staff, and even fly in the airspace to get a feel,
VATUSA has several "Major Airports" the full List can be found here
http://www.vatusa.net/major_apt_list.phpEach of these airports will require a bit of additional training after you get certified on a non Major position,
and last but not least, As a new member, you may find Busy airports very intimidating, and most people find it alot more comfortable to control Smaller airports to build the experiance
hope this helps