For me, my absolute easiest-to-play bass is my Olinto P with La Bella Deep Talkin' Flats, which are "notoriously" some of the stiffest strings on the market. I can play with an incredibly light touch, left & right hands.
There's so much more that goes into playability than just string stiffness. Obviously, a good setup is key too. Stiff strings + high action sounds like a miserable combination. Neck shape + your hand preferences are also a big thing.
Another thing i found is, the stiffer the string, the lighter and faster i can play with my right hand. Looser strings will pull with my finger when i just want my finger to sorta slide off the top of the string. It's hard to explain. Sorta like how a stiff sports car suspension is more responsive and you can feel the road surface better, when compared to a mushy comfort suspension that takes more time sloshing back and forth when changing directly.
For example, Capleton's "That Day Will Come." The guitar has some 16th notes before the second half of the phrase. We like to double that up on bass sometimes. It's WAY easier to play on my bass with the DTFs than my other basses. I can do it without trying on the DTFs. On the Rounds or Tapes it's a lot of work to get the correct right-hand touch to get those 16th notes articulate and locked with the guitar, and it's more fatiguing too.
My other basses have Copper-Tapes, Gold-White Tapes, Superpolished Rounds, and Stainless Rounds. (All La Bella.)