I just adore NCIS:New Orleans
. I also love the original, but can't stand Los Angeles. I have no idea why, but I really can't watch LA spin-off, though I hear only good things about it. It was similar with me and CSI. I liked the original until they started to 'force' Sidle/Grissom romance and loved Miami, but can't watch New York or Cyber.
Another spin-off that I just love is Boston Legal
. I think it was done right in all ways, but you have to know what you watch. It's courtroom drama yes, but with a healthy dose of comedy that people sometimes don't get. It also has two of my favorite TV/Movie actors, Spader and Shatner
I loved Torchwood
until Children of Earth (which I think was executed a bit poorly, at least the last/last two episodes), but curiously, I don't like Doctor Who.
The last spin-off that I really enjoy were the earlier seasons of Law&Order: Special Victims Unit
and all seasons of L&O: Criminal Intent
where they had Goren/Eames as main detectives. I also surprisingly enjoyed UK
version, it had something special that American spin-offs didn't have.