This is a loaded question indeed. I feel there are highs and lows in each company. For instance, I have a Ithaca 7E that is one of the finest guns period, and then I've seen a 4E which must have rolled off the line on a Friday. Foxes were all over the place. Smiths and Parkers more even keel.
So that leaves us with Fox...Beautiful product, financial mess so had to cut corners (especially engraving). That takes Fox out of the top.
Next is Ithaca. IMO, they put out some VERY nice guns in the Crass and Lewis era but when they changed the Flues the frames were strong looking but in reality, weaker. Also, just not very good looking.
So it boiles down to Fox and Ithaca as the bottom 2 of the big 4. And I think that (and I could be wrong) but most anyone would rather own a Fox than an Ithaca.