There are a number of product categories that I can't recommend based on personal experience.  Just about everything hair-related falls in that category. Fortunately, the Road Test team at Real Simple magazine tested 110 different hair conditioners for their June issue.  Here are their top nine picks:

Best All-Around: Rusk Sensories Wellness Bedew Hydrating Conditioner $13.95 at Buy.com
Best for Fine Hair: L'Oréal Paris EverPure Sulfate-Free Volume Conditioner $5.97 at Walmart.com
Best for Damaged Hair: Garnier Fructis Triple Nutrition Fortifying Cream Conditioner $4.29 at Drugstore.com
Best for Itchy Scalps: Klorane Conditioner With Oat Milk $14 at Drugstore.com

Best Scent: Paul Mitchell Tea Tree Lavender Mint Moisturizing Conditioner $10.87 at Amazon.com
Best Shine: Fekkai Brilliant Glossing Conditioner $9-35 at Amazon.com
Best All-Natural: EvolvH Ultra-Shine Moisture Conditioner $25 at EvolvH.com
Best Leave-In: Profound Beauty Hush Time-Out Treatment $23.99 at SleekHair.com
Best Deep Conditioner: Nexxus Humectress Hydrating Treatment $14.99 at Walgreens.com