I don't really care for being at home and watching tv for series. My tv is on about an hour a week. However, I watched quite a few series in my life. But most of em are really slow to me, in the way that the "once a week"-pace doesn't cut it for me. I'm the type of guy that sits down and watches 20 hours straight for a day (and would probably just skip sleep). And also, there's some series that I've watched long enough to at some point realise it's not interesting anymore.
I watched the first 20 seasons of the simpsons a few years ago, within 1,5 month. And I still was attending university then. So I did miss out on some sleep, lol. But after those I caught up until where they were back then (in 2007 or so), I wanted to go on at a pace like I was, and that was, along with the reason that I didn't think it was that good anymore since a few seasons, a good reason to not follow it anymore.
I watched Desperate housewives for a while, but that was when I had to catch up cause I got into it later. Also here, that change of not having that rigorous schedule of watching it is a big letdown for me. And if I rather finish up series than remind myself "oh, I was watching this". Especially if there's a big plot going on through multiple seasons.
Series I did watch and finish (until where they are now); Max Headroom, Dexter, The Sarah Conner Chronicles, Pushing Daisies, Heroes, The Inside, The 4400, Twin Peaks, Transformers G1 (so actually the US/European shows. Never got into the Japanese). Carnivale, Futurama, The Big Bang Theory, Louie, True blood, Firefly, Life with Louie, Reaper and I've probably seen everything Beavis & Butt-head.
Recently I went through 9 seasons of Teenage Mutant Ninja Turtles (185 episodes; in a week). The 10th is really hard to come by, but I'll surely check that out if I can get it somewhere.
There's a few series I'm holding off for now. Those being Californication and The walking dead. I'll watch those when the seasons are done, and watch a season back to back over a day or so. Yeah, and Warehouse 13, I liked the first season, so I'll keep that in the back for when I have no clue what I can watch.
Might have forgotten some series, but that's a rough outline of what I watched. The biggest problem I have, and I kinda learned from that. The 4400, Heroes, Firefly, The inside, Pushing Daisies and Carnivale all got cancelled at some point. It really depends on if they know that in advance if the series is worth watching and the creators make a decent end. The 4400 was cancelled somewhere after a season, so they didn't have an end to it. Heroes, same. Carnivale... those are books, so I might read those. Firefly did get an awesome movie though.
As for owning DVD's... I have 2 seasons of Heroes. That's all.
I do have a thing with the CSI series... those are really the only fillers I might have to just watch as an off-episode.