I'm currently about to play both games (are bought and installed). Played BL 1 and 2. Do either one have spoilers about the other (so I could play the unspoiled one first)
Borderlands: The Presequel is between Borderlands 2 (the sequel) and Borderlands 1.
And here's a quote from Tales from the Borderlands FAQ:
(5) When and where in the Borderlands timeline is this game set? During the Tales from the Borderlands SXSW panel, it was mentioned that the game takes place in Pandora after Borderlands 2 and its DLC.