My first bass in 1971 was a medium scale Gibson EB-something. It was strung with round wounds. I played this bass for about two years and, being a NOOB I didn't know shite about strings, so when it was time for new strings I just bought whatever the guy in the music store recommended.
In 1973 I bought a Gibson Ripper that was strung with flat wounds (brand unknown). I thought they were HORRIBLE strings - no zing, and they felt like bridge cables, so the next day I reverted to rounds. From then until 1980 I played only rounds - either Rotosound 66's or GHS Boomers.
Then I quit gigging for 29 years (college, job, family, etc.).
In 2008 I started gigging again. I quickly gravitated towards flat wounds. My theory is that older bassists (I'm 62) are more likely than younger bassists to try and like flat wounds (and thus the increasing popularity of flats - aging baby boomers). I tried D'Addario Chromes and liked the bright thump but found the tension a little too high. Then I tried and LOVED TI Jazz Flats (woody, organic, uprighty!), and played them for several years. One day I was unstrapping my bass to put it on the guitar stand and the G string snapped at the bridge (still not sure exactly what happened, bass was a G&L JB-2))! After this I couldn't afford another set of TI's ($70 a set!) so I am now playing D'Addario Tapewounds (clear, strong fundamental tone). I really like them, but still plan to get another set of TI Jazz Flats some day.
I have also played and liked GHS Pressurewounds (beautiful scooped tone) - I haven't decided if I prefer them over the tape wounds, but I'm going to put restring my main gigging bass with them soon - sometimes change is good.
Strings are one thing I tend to obsess about. If money was no object I can think of 10-15 string sets I would love to try (all flats, tapes or ground/half rounds, no rounds). Until then I'll be curious and never 100% satisfied that I've found the "best" string.