Typically I try and stick with synthesis that sell to the NPC about the same as the cost to make them, it's been working out so far. Then I just craft certain items that sell fast and are cheap to make in order to supplement the cost of crafting. There are going to be certain classes that are just expensive to level, in that case I'll switch over to leves. But the way things are now seem to be fine. If anything, gatherer's just need to stop pricing so high.