I enjoy solo questing, but this game doesn't really seem geared for that (given you can level multiple classes on a single character; there's no way anyone could put in enough content for that), so in the context of what's viable for FFXIV, I'd say a mixture of leves, dungeons (if they existed), and soloing more difficult mobs for good exp. Camping can be fun, but it gets old fast. I enjoy having a choice in what I want to do with my time.