Those are all quality keyboards, though I haven't used any except the Filco with browns, and that not much. I would say the Ducky is going to be about the same quality as the PLU and the Noppoo. The leopold is a bit nicer, about the same as the filco. Each of the last two is better in different aspects, from those that I've seen.
Honestly, you can't really go wrong, so I would get whichever you can get delivered for the least amount of money.
If time is a factor, both the leopold and the filco could be a problem, as they are currently unavailable nearly everywhere I'm aware of.