Ledoyen has the best food of the three by far -- very great ingredients, highly balanced and able cooking. But the other two are palace restaurants, with resources that are much higher, rooms that are brand new and magnificent. Their chefs are similar in that they are highly skilled chefs, capable of almost anything. Yet le Bristol is more food lover oriented, especially with its famous chicken, or the sweetbread. It is very comfortable and luxurious, both dining rooms (winter and summer) are lovely. Le Meurice's setting is purely Versailles like, and their waiting staff is world class, head by a former Louis XV-Ducasse in Monaco captain (Morandini I think). Savory food is boring, sophisticated, not without flaw, original. Desserts are to die for.
Le Meurice is more international jetset and rockstars. Le Bristol more happy few, Rostchilds. Ledoyen like a respectable talented old lady.
Only Ledoyen has a good deal for lunch. The other two have lunch deals that are very subpar compared with their usual food.
You will find Ledoyen pics on my picasa ( picasaweb.google.fr/zejulot ). I had pics from le Meurice but they got stolen with my camera.