I tried out the Ritz-Carlton, Le Meridien, St. Regis and W during a one-week hotel-hopping expedition

Ritz-Carlton:
* Attractive rate (130€)
* Room was nice and well-sized for not being a suite
* The service was warm and polite, and at times very good
* Tried the gym (good enough) and pools (calm and quiet, though the view sucks as you are surrounded by tall buildings)
* The only thing that wasn't great was the breakfast - nothing wrong as such, but quite a small selection

Le Meridien:
* The cheapest of the bunch, obviously
* I really liked this one, especially the service (probably the best out of the four, which I did not expect)
* The breakfast was the standout here with the best selection I've seen in a while and well maintained too
* My room was ok, nothing special
* Gym was on the Hilton side, but was well equipped though often quite full
* The pool area is nice, has a resorty feel to it and it was easy to relax. Good views too.
* The lounge was surprisingly positive with lots of space, great views, small but good selection of food and very attentive service

W:
* I'm still not sure if I like the clubby vibe of this brand or not, but I of course knew what I was getting into
* Great room with all the usual quirks
* The breakfast was good, though for some reason it just didn't click for me, maybe I just had a bad morning
* The pool area is fun and has fantastic views of the Petronas towers, great for selfies
* The service was a bit of a mix, overall of course good, but I didn't feel as welcome as at Le Meridien

St. Regis:
* Used an SNA here and got the Caroline Astor suite which was large and elegant
* The breakfast was high quality, though it was completely packed so felt rushed. No blame to the staff who handled everything well
* Didn't try the pool, but walked through the area a few times and it look relaxing
* The gym was compact, but I liked the view and windows
* The service was very warm and polite, but I had a few annoying waits that seemed unnecessary. Again, difficult to fault the staff here as such, but I felt better treated at LM

Summary: on price/quality Le Meridien wins by a large margin, I would definitely stay there again. With the other three I would pick carefully also keeping in mind location