I have a lot of experience with both. Precision Flats lights are MUCH stiffer than LTF, and have worse tone, so I see no point in them over LTF. Precision flats are difficult to fret and feel "hard" to me, like they hurt the tips of your fretting fingers.
LTF is THE old school flatwould in my opinion. The best tone, and the easiest to play while not feeling loose either. I see no point in any other string if you are going to old school P thump. (Just want out for bad G strings that will have a "sitar" like chime, I've had to get a few replacements from LaBella but once right, you are golden)
Since Dunlop and TIs are also mentioned here, I have experience with those also. I LOVE TIs on a jazz bass - no better feel or tone for that bass playing fingerstyle, IMO. They are so soft and so easy to fret, but the tension is perfect for playing near the J bass bridge. They are too loose for a Stingray or Precision bass, though, IMO. They shine on a thinner neck. To me the diameter feels too thin on a P or Ray, and too loose for the finger style I like to play when played closer to the neck.
Dunlops are cool, they are actually a LOT like a more flexible Precision Flat. They sounded amazing on a 3 band Stringray I had. However, they have the WORST silk in the game. I don't like the thick, shiny, black color, but even worse on all three sets I tried the silk became untangled when installing them. What a mess.
LTF and TI are the only flats I will use, and I've tried them all. I will say that Cobalt flats sound OK on a Stingray, but I also find them a bit too stiff (yes, lights) and I am finding that I am LOVING Ken Smith light compressors on my Ray now. Super low tension and a great feel, plus punchy, warm tone for my Stingray, and I dislike most rounds.