In response to the OP; you said, " The Nolan's Cross stones and the various triangle stones don't really do much for me."
For me, the stones of the cross, and apparently the Tree of Life, are the most tangible evidence that something has occurred on the island that is unusual. The other evidence is either missing or subjective in one way or another. However, those massive boulders are not subjective. Quite the contrary, they seem very hard to reasonably explain.
One of the few things that the tv show has provided for me is that look at one of the stones in Nolan's Cross. (I think it was the scene where one of the brothers stood on top of the rock) I had not realized just how large those rocks are, which speaks to how difficult it would be to move them. While it is true that Nature does occasionally arrange things in a straight line, I'm not aware of any instance where Nature makes crosses. I also believe I have read or heard that those rocks are not indigenous to the island; I'm not sure about that, however. If so, wow.
So, for me, the best "evidence" on the island is still very tangible and touchable (or standable!). The alignment of those boulders is evidence of man's hand, in my opinion. Who's hand, and when? I haven't a clue.