The older the server, the higher the levels will be of most of the players. Also, on the older servers, many of the low level characters are secondary characters for players with high level characters, which means they are often twinked with items not normally available to players at that level. Of course, these players will also be more familiar with the zones and with how to properly play the game than many newer players, and there are likely to be more items floating around for sale than on the newer servers, driving the prices down somewhat. If you are from Europe, you may want to consider Solusek Ro, which is kind of the unofficial European server, and has a large German and French Speaking population on it. Probably the biggest consideration is server population.
Many servers suffer from some serious over-crowding issues.
The game was designed to handle about 1,500 people at peak, but several servers go into the 2,000 range. The more people on at a given time, the more competition there is for kills. If you aren't looking to meet a friend who is already established on a given server, I would highly suggest that you find a server with a lower number of players. Stats You chose your character's stats when you create it, and have to live with the decision thereafter. There is no one perfect way to set up an individual character class.