id go for campag! quote "shimano are better with spare parts" thats usually cause they break quicker than campag, saying that theres little between ultegra and centaur i have centaur on my bike and had no probs over last two years and my mates been running ultegra with no probs.
The sensible option is get whats compatible with your other bike then when upgrading you can switch parts between the two?
The sensible option is get whats compatible with your other bike then when upgrading you can switch parts between the two?