I've spent some time experimenting and I've found combinations that really work with my style and my basses.
StingRay:
Stainless steel rounds, in my case Rotosound RS66's, have been the best in my experience. I've had a myriad of flats on this bass trying to chase Bernard Edwards' CHIC tone, but I've found a set of played in Roto's just belongs on this bass.
Fretless Jazz:
Same with the 'Ray. This one is a Frankenstein work by myself, and I'm thinking of getting a new Warmoth neck perhaps but with this pickup configuration the Roto's win for me once again
SX P:
I had rounds on this for ages, tried flats for a second, but I've actually settled on D'addario tapewounds. This particular bass has EMG's, so it can get fairly bright when I need it and super dark as well.
Guild Starfire:
At the moment, LaBella Flatwounds are great on this, and although lacking a little in the top end for my liking I don't think that's really what this bass is meant for.
I've shifted my collection around a little and some string choices have changed.
My StingRay still has Roto rounds, and I've got a set of those back on my SX P bass, which has since gotten a brass nut and been used for down tuning. The Starfire still has the LaBella's which are getting to be almost a year old. I go back and forth about whether I want to put tape wounds on the Starfire, but it's pretty noisy as is. In lieu of the fretless Jazz, I have acquired a 2010's MiM Fender Jazz Bass, which had Rotosounds for a little but now has LaBella's, which I think I prefer. I went with the slightly lighter 43-103 set, which retains just a little more brightness than the standard set as well as being lower tension, but not too floppy.