Legacy is great. My three friends are joining legacy as opposed to my one person leaving.

- Most people only had one or two level 50 classes. A lot of people played XIV casually. So you'll easily find people to do things with. Especially with duty finder being cross server.
Looked up data: 4.41% of all players had all 50's at 1.0's end. So there will be plenty to level with, plus arcanist. Source: http://xivpads.com/?Census/1.0/Classes

- The economy will stabilize faster. Give it a few weeks. For non legacy, give it a few months since they have to figure out what is in demand, what others will want, where to get things, etc. Legacy players have a rough idea of where to get a lot of things and how to get em in ARR. Stuff was all across the market board by the end of phase 4.

- More established linkshells from the start. Meaning you'll see a lot less of those launch MMO linkshells that last a few days/weeks then just dissipate as members slowly leave or stop playing altogether.

- More people willing/able to help. Including myself. <3