NAD M33 and which speakers?

If the PuriFi implementation in the NAD is anything like the one available through Apollon and other assembly houses, the M33 should do fine with any speaker that you like. The PuriFi amps are load invariant and interact less with speakers than just about anything else on the market. So it comes down to the speakers that you think match your own tastes.

That amp will drive anything well so you have your choice of pretty much anything. 

Start with whatever Harbeth you can afford and take it from there...

I have a pair of the Amphion 7LS and I am running them off a similar integrated streaming amp set up and it sounds pretty incredible so I would imagine the Argon 3S would work excellently as well!

I use my M33 with Paradigm 3F floor speakers. Love the sound.  I haven’t heard the Persona B stand speakers, but I would certainly give them a listen.  Paradigm Persona high end speakers are beautifully constructed with choice of several colours and produce beautiful sound.  Made in Canada with not a huge share of the American market.  Selling them in Canada, they move very quickly.  Good Luck.