One big factor: what size bike? 54cm and smaller LHT frames come only in 26".

I guess I'm saying don't decide on 700c if you ride a 50cm frame. 26" makes for much better geometry in that size.

You can usually find big touring bikes with 26" wheels, but the 700c wheels just don't fit small frames well, especially with clearance for fattish tires and fenders.