What is your price range? Go look at what bikes are available in that price range. Then look to see how they are equipped. Cannondale uses FSA cranks and mine creaks constantly and I likely won't buy another bike with FSA crank. What gearing? It can be costly changing out a derailleur and cassette. How particular are you about color? I won't ride an invisible black bike; I want to be seen. 105 or Ultegra? CF or aluminum? SRAM or Shimano? Lots of the fancier higher end endurance bikes have new technology on them to make the ride better. What type of roads do you want to ride and how wide a tire do you want the frame to accommodate? These are some of the criteria you can use to help prioritize which bikes you might wish to test ride. Are you willing to purchase online based on specs alone? I don't know how many offer free shipping on returns if you are dissatisfied.
When I purchased my last bike, I went and rode four different brands and a couple of different models for comparison. I was looking at CF and had never ridden one. Bikes also had sloping top tubes since my previous bike purchase. I wanted to try as many bikes as possible.