The HD vs HH (I have both)...I have the HD in the HD2 Funayaki model - less belly & nice straight cutting edge.
HD slightly less stain resistant (not that it patinas heavily or stains, it is hardly noticeable) than the HH, but has better edge retention - both sharpen easily.
The comparison between HD & Fuji is a personal choice between likes & dislikes of carbon steel vs semi/stainless.
Caring for the carbon steel is no more difficult than caring for a stainless knife (I am working from the assumption that you peeps treat them correctly.....wipe down, wash & store dry etc...)
I have had some very good honyaki white steel & other carbon units - yes, they take an awesome edge & sharpen easily.....BUT my biggest gripe was the edge....my type of food prep always includes acidic items like onions, tomatoes etc - this is where I dislike carbon steel - the edge rapidly dulls after the first few cuts (while the HD in the same scenario will still be screaming sharp for many, many more cuts & prepping.....so I have moved on to using stainless/semi stainless.
If you want carbon, go Fuji...
If you want a lasting sharp cutter, go HD.
It's a personal choice which I believe most of us knife nuts get to make - once there, you move forward to what you prefer ultimately.