Originally Posted by kingston

I don't have any long-term test data to back it up, but assuming we're just talking about Shimano, I would go for 105 if my primary concern were long term reliability. Tiagra has more plastic parts than 105 so it's probably not as durable. My guess is that Ultegra is at least as durable as 105, while Dura Ace may be slightly less. They will all last a very long time if you take care of them and don't mind replacing those crappy HT bottom brackets all the time.

Originally Posted by Larry77

I've had Tiagra, 105, Ultegra, and Dura Ace...I would choose 105 if I wanted long-term durability. That being said, most of my bikes have been full Ultegra and I've never had an issue with durability.