I've just bought these boots in black leather, good choice :)
I bought them in a shop so I could try them on and didn't see all the other colours on offer so can not really be of help, but personally I like the brown nubuck ones from your options. And at almost half price I can't blame you for choosing one of those colours! I did need black but am tempted to buy more now!
Size wise, I'm usually between a 4 and a 5 and although I have other Fly boots in a 5, I got these in a 4 and fit well. The calf width is quite narrow and the 4's fit me perfectly, 5's were a bit too big on the calf.
Hope you like them!