In Drinkmate vs Sodastream, a Drinkmate is better than a Sodastream(carbonated beverage maker).
The main differentiating factor between them is that a Drinkmate can carbonate virtually any liquid.
However, with a Sodastream you can only carbonated water, sparkling water, or tonic water.
In regards to price, and usability they are virtually identical, therefore, a Drinkmate is better.