I think the original Law & Order is pretty great, and quite underrated. It has a lot of character and has aged better than a lot of stuff from the 90s.

I'd say seasons 4 to 10 were great. Maybe up to 11. After that, it's good until maybe season 16 or so. Then it gets pretty bad for a while.

I know the latter seasons were considered a 'return to form' by a lot of people, but I don't think that stuff aged very well.

Tried to watch a bit of the last season and it was atrocious.