Well, I'm not sure where in the UK you can source those keyboards other than eBay
I cant say much which is better than the others, that thing does not apply in our (keyboard) world
Its more of a personal taste and habit
Maybe hinting your bf in a way to know which he prefer would be better, both keyboards are not cheap and you wanna spot on
Both boards can be considered high end keyboards for topre lover, you dont have to worry
A lot of topre lover here dedicated their life to HHKB , so if at the end of the day he didnt get the hint, you might wanna consider HHKB