As Raisin said, floating near the edge gives a lot of control of when you want to time grabbing the edge, unlike other characters, peach can't refresh her ledge invincibility very quickly so this is the next best thing. It also has the added advantage that you still have control of covering recoveries that go onto the stage as well.
Wavedash back is fast if you are already in the position, it doesn't happen too often though. A bonus to this is that you get to keep your float if you should need it.
Moonwalk is technically the fastest but is just for style points really.
If you are trying to get to the edge from a long distance you can run towards the edge, do the slow turn around by dashing in the other direction near the edge, cancel the turn around animation with an instant float and grab edge. Rolling and then floating is a simplified version of this.
Lastly if you have a turnip you can throw it to change directions in the air and grab the edge. This usually happens when you knock someone off stage, instinctively pull a turnip and quickly notice that an edge hog will probably kill over a turnip snipe attempt.