89 Fender Corona 60's reissue P: TI flats. Just sounds good that way. Love the tone and the response. They allow me to add tonal and stylistic inflections that other strings cannot. While they have their limitations, the reason they're on this bass is because that's what I wanted this bass to be for in the first place. Sounds great played up close to the neck.
2011 Fender American Special P, modified with SPB3 Quarter Pounder, different tuners, Hipshot Type A bridge: At present it has D'Addario Tapewounds, just because I felt like it. It may eventually get Rotosound 66s back on it, though, as it's a great rock bass. I may revert it back to more of an old-school state, though. I generally have kept Fender 7150s on it in the past.
2012 MIM Fender Jazz: D'Addario Balanced Tension Super Light Nickel Rounds. They're pretty light, but I don't really like heavy strings. I almost never use effects, but with this one, I like to focus on the bridge pickup and run it through a Boss CEB-3 chorus, for that sort of classic 80's effect. I love the brightness and pliability of these strings, and they just work well this way.
98 Warwick Streamer LX: TI flats at the moment, although I have used a variety of strings on it in the past. This thing is a ridiculously bright instrument, and I love the tonal quality of TI flats, so it seemed like a good formula. I've tried other flats on this bass, and these are the only ones that work on it. Partly, it reduces that excessive brightness that I don't need right now, and partly its tendency to get bright allows me to bring out some of those interesting tones that you can get out of TIs. It's a lot of fun, given the tonal variety available from this instrument.
I should add that I am extremely prone to switching strings at any moment, and have tried quite a few different varieties, so just because I said what's on what bass now doesn't mean they'll be on them next week.