Basically, your lifestyle determines where and either a house, townhouse or condo you would like to buy.
Downtown is more suitable to professionals, young couple, small family without kids (or one). It is convenient to everything, even walk to work. It is an urban living lifestyle. You will enjoy all amenities around, bars, cafes, museums, all kinds of outdoor events, festivals, etc. However, it is very expensive to buy a house, (town house is less pricey) tax will be high…. Condo is another alternative, you pay condo fee, but you don’t need to take care of lawn and you could enjoy the facilities such as gym/swimming pool.
It is unfair to say if Barrhaven, Orleans or Kanata is better than others, there are good and bad spots / communities in these three regions. You have to do your study. Bottom line, you have to like what you bought, everyonelse's opinion is just reference.