There are a few shows I watch - and re-watch ... Blake's 7, and Star Trek, Voyager, to name 2 ... but when it comes to obsession, there is really only one answer -
I may have been watching Buffy, the Vampire Slayer for a few years - but it is still my current obsession. I love the show, and re-watch it ... I read Spuffy fan-fic ... and even scribble a bit myself.
The Ultimate Buffy Quotes - with some of the soundtrack to OMWF-