Model 75 is the best rifle they ever made but discounting that, the old underlever model 50 is my favourite.
Out of the guns/ era you mention I have had the 46. I chose it over the 52 in the shop as it looked and handled better. Unfortunately, it turned out to be a lemon and went back.
If i had the choice again I'd still go for the underlever for the same reasons. More likely, I'd go for one of their break barrels. The 52 is a very substantial unit and seems to lack the sleek looks and handiness that Diana does well in other formats.