What character do you think had the most untapped potential and why? What do you imagine they could've done with the character that they didn't?
Pesonally, I think all the listed characters could've gone some really interesting places had the writers really tackled their stories and if time allowed.
Halfrek in my opinion is the absolute greatest tragedy though. When she and Spike had the moment in 'older and far away'- I only wish (no pun intended) that that story was expanded. Olivia too should definitely have been given more story.