I would have thought the most influential holes are those with unique characteristics that are subsequently adopted or borrowed.
In that regard, I would not have thought of the 17th at TPC Sawgrass as influential for its island green. I am sure there were previous island greens. The par 5 17th at Cherry Hills comes immediately to mind and I am sure there were others, par 3s included, that preceded 17. What I think makes it influential is the theatre atmosphere, not necessarily being an island green. The 16th? at TPC Scottsdale, although not an island green, replicates a similar atmosphere as 17 at Sawgrass.
Likewise I do not see how the Road Hole has been influential. Not many courses have a tee shot over railway barns and a paved road and wall running behind the green. NGLA has a hole inspired by it in a general sense. How has it been influential? Bunkering?
I would have thought that a hole like #10 at Riviera would be much more influential, being a reachable, downhill, risk / reward par 4.
I love #4 Spyglass. To me, it is the long, tiered diagonal green running between sand dunes that makes it especially unique. As far as it being influential, I cannot say I know of attempts to copy it although I would like to see similar holes. I am sure most of you have seen a lot more than me and can say if it has been influential and if so, what is the evidence?
Re #6 Pacific Dunes, I love the entire course but do not think it has been around long enough to have been influential.
Bob Jenkins