Where it all began. Important to note that this came out in 1978.
It's interesting to see the original manga chapter and compare it with the two adaptations.
Both anime adaptations took some liberties here and there.
The original anime was funnier. Because it had less time, it cut significant portions of the chapter. And the way Ataru was chasing Lum became a montage was arguably the best part.
Ataru using a random gadget to get her bra somehow became an iconic moment.
But the Remake was the most faithful. Though it wasn't 1:1 with the manga.
Ataru didn't keep the bra for a day in the Remake for example. And also, the Remake added some slight changes which makes it more obvious how/why Lum fell for Ataru. Whereas in the original it was pretty much a mystery.