Certainly personal taste. And there’s no right answer. Using La Bella Low Tension Flats on the G to E string and a La Bella Deep Talkin Bass on the low B. The 1.28 regular tension is great on the B.
When it comes to strings, gauges and brands, I feel each bass (brand/model) react differently to different brands and gauges of strings. My staring point is Hard Rockin Steels for rounds and Chromes for flats. Having said that, I have TI flats on a P bass, La Bella Hofner shotlrtscale flats on a violin bass, Cobalts on another etc., etc. The bass and my ears let me know.
My 2 cents...worth every penny.
Here’s a lengthy iPhone shot Motown thing with the PV w/ flats. There’s some upper register (Sir Duke) stuff later in the video.
Use headphones or inears.