If you are a new player, do you want to join an old server? The same answer apply for every new player. People want to be at the top, so they join new server. People who failed to become the top either stay casual and become punching bag or jump to another server with hope they can be a winner.
This is how this game designed, all good rewards stay behind ranking walls which involve pvp content.
If you join an old server after few days, weeks or months the chance you gonna stay at the bottom forever is pretty high unless you pay * load of money to catch up and not everyone can affort to pay thousands of USD into a game.
So it's depend on each person, if you want a very competitive server and have money to spend. Go ahead and pick old server, none bat an eye. But if you choose the new one then prepare for the huge players drop after few weeks.