Usually get to stay at the Bristol on business - so have extended this to private stays as well. Enjoy the hotel overall - it's classic and classy. Sure, the Meridien is more modern and the Imperial more gold leaf around every corner, but the Bristol is classic luxury. The bar still allows smoking, the front desk is in wood that might / might not be from some tropical forest - this is a hotel that has always been in place and reminds of a good old time.
The restaurant is a classic, though sometimes I arrive too late and need to enjoy the Wuerschtelbude up front. Location is a dream - just a step away from the operahouse.
Overall, if you are the type for modern hotels with house music in the elevators, go for the Meridien, go to the Imperial for over the top luxury, but if you enjoy old-school, "noblesse oblige" luxury, head to the BristolMore