I personally really like BazaarVoice, because it provides a lot of customisation options and has some really advanced functionality. That said, BazaarVoice is quite expensive and it’s subscription-based.

The default Magento module is actually quite good, although you might want to use additional module or work with your developer to get more from it.

BazaarVoice also has schema support, making it easier to get the ratings schema appearing on your product listings.