My personal preferences should not affect your decision at all, since they are purely my preferences.
However, since you asked. The MF A3 is a very nice looking piece of gear and it's made in Britain. I believe NAD components are manufactured somewhere in Asia even though the company is Canadian owned. The stability and headroom on both will be tremendous. Without benchtests I couldn't say which is the superior performer, both have very robust amp sections. Personally I'd get the MF A3 for the simple fact it looks nicer, has a slim profile, it's not made in Asia, and my personal experience with dual mono amplifiers has been good.
Of those speakers I have no experience with Castle, Canton, or Silverline. I've owned a pair of Paradigm Studio 20s, they where version 1. I've listened to the V3 in a showroom. The setup was not appropriate, however they still sounded great. The B&W CM series speakers have excellent cabinet build quality and finish. I've also owned some NHT speakers, however they are quite a bit different from the Classic 3. I've not heard anyone complain about the Classic 3, and I have also not heard a lot of praise either. Of course that doesn't mean they aren't good. NHT has a good reputation, I'm sure they are great speakers. Out of curiousity I'd end up picking those more than likely. Holding out for a pair of used CM5s could be costly though.