As the title says, any recommendations for the best helicopter offering for P3D, particularly with reference to the flight model?
That’s a hard one to reply as P3D doesn’t do that much of a good job with helicopter flight models.
I would perhaps recommend Carlos Palacio’s AW139. The 139 is a stable platform so you don’t get to miss the instability helicopters inherently have. This one’s free.
Following the same logic, the CeraSim B412 is also a good helicopter.
Yeh, that was kind of my point. Knowing P3D is not the best for helicopters I wondered what was regarded the best . A shame the Dodosim 206 never got ported to P3D, I have not heard of something with a similarly good flight model for P3D - could do with one for exploring the scenery up close. 
There’s something you can try as well: HTR. It comes with some profiles and you can make your own. It’s a bit of work but well worth it.
if you looking for difficult ones to fly, I recommend the ND AS 350, the Mp Design Studios Aerospatiale Gazelle, and LAMA SA315. In P3D there very good on flight dynamics. Milviz UH1C/ UH1H is pretty accurate too. you can get into a vortex ring state on that one if your descent is too fast .