On my own tourer and most of those I have built for customers, I have used SRAM chains. They seem to shift well and be reasonably durable. On my own bikes, I use the cheapest models and haven't seen any degradation in performance or durability. Honestly, though, I don't think there is a big difference in the quality of any of these chains. Riding conditions and maintenance will likely have a much bigger impact. However, if you do go with Shimano, I recommend a connector link rather than messing with Shimano's special pins.