I stayed at both LM Etoile and Westin back in January. Had stayed at LM Etoile before, first time back after the updates. Missed the lounge but everything else was fine. Did not get suite upgrade this time but was given a corner room which is slightly larger, the updated room is modern and well appointed (no more separate small room for toilet). The duty manager came out to welcome me back and appreciate my business, nice touch. The surrounding area is convenient enough for me, AF bus drop off is right across street, the metro station and PER station are very close by. Some restaurants in walking distance and a grocery store in building cross street.
Prefer the location of Westin, pretty much in walking distance for everywhere I wanted to be for the trip. Room I had there was very comfortable. Every staff I encountered were very helpful, excellent concierges.
Never stayed at Prince de Galles and LM Montparnasse. Location of PdG is good. LM Montparnasse is further down, probably another 20 more minutes for AF bus ride than LM Etoile so always felt too tire to get there after long flights.