They are both in very different areas and this is really a question of personal taste.

Lot of people like "the Marais" as this is so Parisian / charming ( I don't).

Both hotels are in safe area : however a little better in the shangri la area. (Marais and especially Bastille are not the safest place on saturday evening)

If I need to pick up one hotel (between both) for a staycation : shangri la hands down.

If you can split your stay between both it may be an idea.