Fender Flatwounds. No, I'm not kidding. I had Thomastiks on my P-bass for a while, everything Andy says is true , but they weren't quite the string for me, at least at this point. The Fender flats are cheap and nothing like Thoms, so I figured what the hey and got some. Pretty stinkin' cool. Lotsa bottom (natch), but good mids and some highs to boot. Good "bark" giving a string-bassish attack, and reasonable sustain. Nice and thumpy, and the high tension helps if you like a strong attack. I think the ones I have are .045-.095, I'm going to go heavier on the next set. Still, a couple of questions. I haven't yet tried Rotosounds, LaBellas, Dean Markleys, or GHS. Tried Chromes , hated 'em. I was thinking about a .050 - .105 or so, so if you're really thrilled with any of the above brands (except Chromes ), lemme know.