First of all go watch The Wire. Pure greatness. It can be hard to get into, as it isn't exactly an easy to follow show, it needs a lot of attention and commitment and its theme might not be easy to relate to. But if you get into it, it's greatness.
Other than that, other excellent shows I picked up over the years:
Band of Brothers, The Sopranos, Breaking Bad, Oz, Dexter, Arrested Development, Firefly, Game of Thrones, Mad Men, Rome, The Shield, Doctor Who, The Newsroom, Sherlock, Luther, Fringe, Homeland, Six Feet Under, Sons of Anarchy, Spartacus, Justified, Battlestar Galactica, Boardwalk Empire, Deadwood, Farscape, Star Trek, X-Files, Entourage, Californication, Suits, The Walking Dead, Vikings, Lost (even if after a while it stops making sense), Prison Break's first season, How i met your Mother.
Burn notice ( recommended ), Dexter, Game of Thrones, True blood, Arrow, The Walking Dead, Rome, there's probably more, but can't remember at this point.
My Name in Earl !!! fist season very good, then decreasing but still good
but all listed are series nad no "tv shows" in my opinion. Good TV-Shows - no one.
if u like sci fi i would strongly recomend Star trek series (Enterprice/Voyager) <- awesome series with all the things u just wanted.. Action Fantasy Adventurous Comedy... And Stargate series are really good aswell SG1 and Atlantis there is cuz im still on Atlantis and i watch at least 1 show every evening :D
Other than that, other excellent shows I picked up over the years:
Band of Brothers, The Sopranos, Breaking Bad, Oz, Dexter, Arrested Development, Firefly, Game of Thrones, Mad Men, Rome, The Shield, Doctor Who, The Newsroom, Sherlock, Luther, Fringe, Homeland, Six Feet Under, Sons of Anarchy, Spartacus, Justified, Battlestar Galactica, Boardwalk Empire, Deadwood, Farscape, Star Trek, X-Files, Entourage, Californication, Suits, The Walking Dead, Vikings, Lost (even if after a while it stops making sense), Prison Break's first season, How i met your Mother.
Hope I helped.
Lost (Ended)
Person of Interest ( season 2 just ended)
Dexter (next season last :( )
Breaking bad (next half of season last :( )
Special mentions: Fringe, Band of brothers, True blood.
but all listed are series nad no "tv shows" in my opinion. Good TV-Shows - no one.