A French pleat will give you a more stylized structured look with your drapery panel fullness. It will look more custom. Rod pockets are gathered on the rod so you won't have the depth that you get with a structured pleat. There's no better or worse, just personal preference to your end result.

I'll add that the French pleat, along with the more custom, structured look also has a more polished look that lends itself well to more formal feeling. Rod pockets are a little more casual.

Rod pocket headings do not traverse well at all. They are the heading of choice for ready mades. French pleat is an all round better choice. Uses more fabric but as both above have mentioned, is a custom look.