I am kind of on the fence on which one might be a little better for my character.
You can 'mostly' keep up with the higher end gear for your character level. You do get to craft nice purples when you get to level 50 although I am not sure how the grind for these is going to be or how valid they will be a few weeks after someone starts to raid. Not sure what the advantages are beyond that.
Once you get a piece of custom grade gear you can keep modding it all the way to 50. Most of the gear upgrades/replcements happen often enough with questing and random drops that. You can also make offhands for you and your companion.