They're both great knives from great vendors. Being in the US, you'll probably have a better customer service experience with the Gesshin Uraku (on the off chance anything goes wrong).
My one comment on the Gesshin Uraku series is that they're fairly thin and lightweight. That helps make them great cutters and feel very maneuverable in the hands. I personally prefer a slightly heavier usuba, but that's more of personal preference thing. The Ichimonji will most likely be significantly heavier if I know the brands at all.