I've heard alot of good things about the double double hamburger from In And Out, so I was excited to try one when i was in Las Vegas. I've never seen a burger restaurant so crowded before in my life. I had to wait a few minutes to order and then another 10 minutes for the food to be ready. Unfortunately, the fries were undercooked and tasted like a bad homemade batch. The burger was decent with really fresh tasting meat, but I didn't get a good taste of the special sauce in any of my bites. The burger was just slightly above average and the fries awful.
Carl's Jr still has the best tasting burgers that i've ever eaten. My favorite is the Guacamole Bacon burger. It's slightly spicy but juicy and has the right amount of cheese, meat, and sauce in every bite. I also tried a Jalapeno burger, which is much spicier than I expected, but also very good. Carl's also makes a Oreo shake which is addictive.