I really don't have much and half of them were impulse buys on series at Walmart that were very cheap:
Star Trek TOS (complete series) - kind of an essential for me, one of my favorite series ever
Penny Dreadful (season 3)- I haven't watched it yet but I liked the first two seasons and this was dirt cheap so I picked it up
The Simpsons seasons 4,5 and 6 - to me, this is the best period of The Simpsons
The Adventures of Brisco County, Jr. - haven't watched but real cheap and rave reviews
King of Queens season 2 - surprisingly good series
Newsradio Complete series - maybe second only to Seinfeld when it comes to 90s comedies
Quantum Leap seasons 1 and 2 - very cheap, haven't watched yet
Police Squad! - one of the funniest series ever
Twin Peaks complete series - loved it til they solved the murder and then quickly lost interest so haven't watched it all
Happy Days seasons 1-5 - started out as a very nice 50s nostalgic series, then had one truly hilarious season but then it became really repetitive and silly
My Three Sons seasons 1 and 2 - I would say one of the better comedies of the 60s, at least these early seasons
In Search of... complete series - fascinating series hosted by the late great Leonard Nimoy
Jessica Jones season 1 - I like it so far, only on episode 3.
Hawaii 5-0 seasons 1-3 (original) - have only seen the first season but thoroughly enjoyed it
Hogan's Heroes season 1 - silly but fun, the actor who plays the camp kommandant is absolutely hilarious
The Goldbergs season 1 - great series, will eventually get the rest
The Wild Wild West seasons 1-3 - first season in black and white is great, incredible mixture of western, SF adventure, one of the best seasons I have ever seen on tv, next season still very good, haven't watched third yet
True Detective season 1 - the best cop drama series I have ever seen
MASH seasons 1-4 - came in a four pack, the first three seasons are hilarious with genuine touches of compelling drama but season 4 (when Blake and Trapper left) is less so, but still good
Three's Company seasons 1 and 2 - surprisingly entertaining total fluff, I will probably get season 3
I Dream of Jeannie season 1 - only watched a few episodes so far, not a bad show but still haven't gotten into it yet
Sledge Hammer seasons 1 and 2 - not quite as funny as Police Squad! it is still an outstanding series
Archer seasons 1,5,6 and 7 - fantastic comedy and animation, love them all
Wings seasons 1-3 - very cheap and while this is a good series, it's not exactly one of the greats
DC Legends of Tomorrow - impulse buy, haven't watched yetThe Love Boat season 1 vol II and season 2 vol I - I picked these up based entirely on a pilot I watched a few years ago for the series that featured a hilarious story featuring two virgins who married one another and don't have a clue what to do when they are alone together, other episodes are formulaic but fun to see a lot of actors from that period
Bewitched seasons 1-2 - great comedy, I had never seen this series except the color seasons (not very good to be honest) but these early seasons have some genuinely funny scenes, one of the best
Seinfeld complete series - last but not least, the greatest tv series ever