GoT
Dexter
Lost
One Tree Hill when it FIRST ended at the end of S8, but then they brought it back for a 13-ep S9 that I really enjoyed
The OC
Pretty Little Liars
Stargate Atlantis
Angel ending on a cliffhanger; I actually really liked S5 and the final episode would have been great, had there been an S6.
The list goes on to be honest. It would be quicker to list shows that I think *did* end well.