Well, I've tried numerous sets of flats over the years, always looking for that tone for my Pbass (with PV63 pup), which I never found, perhaps because it only exists in my mind. Or is the result of heavy production, as heard on certain recordings I take as reference, including compression with supa dupa tube compressors that cost thousands of bucks.
How would I describe that tone: super thick and creamy and warm and round and plastic and elastic. Or something like that. Like the tone of the great reggae bassists: Flabba, Fams, Robbie etc.
The closest I got was perhaps with a set of LaBella 760FS - but only as regards the E and A strings. D and G were horribly trebly and thin sounding even after six months of daily use.
So it's been about three months now that I have a Fender 9050M set on this Pbass. There's days I sort of like them and there's days I don't. They're pretty much even sounding across all four strings, which is good. Sometimes I have the impression the tone is somewhat hollow (like I also thought about Dunlop flats), some other days they sound kinda alright.
DR Legend were perhaps the best set overall, consistent end even and quite juicy.
Pyramid Gold were also not bad, perhaps not as lively as I would like them to be, which is not much.