The best surge I've had was in UC:3 and it was serpent's bite.
However, i agree that surges generally happen more often in lower DL areas.
Stuff like executor or bracers of war just don't happen for me in surges, though I have to admit a wizard of mine once found BoW in the HMV shop, I was quite surprised.
Afaik Ln dug the bracers up from a grave in griffyard some time ago, so I guess in the end it's all about your personal luck.
Whether it's a surge, random drop, shop merchandise or treasure grave - that's irrelevant.
"Hell is empty and all the devils are here."