For almost every airline in existence I favor the logos from the 60s and 70s. That certainly applies here; my UA favorites are the shield with UNITED through it and the vertical stripe on the tail. The black meatball for CO was the best.

For many of us involved with the airline at the time, the tulip is a bad memory of when upper management all came from the hotel side of the business (United owned Western International, later Westin, at the time). The "wi" in that logo is pretty apparent.