I used to have a customized Washburn headless bass. By customized, I mean I had three pickups on it, similar to a stratocaster. I used fairly light strings, but that's because I liked a snapping, popping, sharp clear sound, because I played a l;ot of slap, and because I often used the bass as a lead instrument. Was also easier on my fingers and allowed me to do some bends. If you want a deeper, more thumping sound, go to heavier strings. It's really all in the sound you want, and how comfortable you want the fingering to be. If you're a beginner, stick someplace in the middle. And if you have a good music store where you get your strings, don't neglect asking the dudes there to advise you.