A truly dispassionate computer program drawing the lines based on geographic continuity would be best.  The problem is the Voting Right Act that requires minorities to be given special treatment.  Such a computer program would probably get thrown out and we'd be back to square one.

The worst case is when we have 60-40 districts.  80-20 is actually better than 60-40, because 60-40 still means the 60 side always wins, with 40% always misrepresented.  At least when it's 80-20, only 20% are misrepresented.

50-50 is best, since it should produce a consistent stream of moderate reps from each party rotating through.  But that's very hard to accomplish such balance in more than maybe 1 or 2 districts.  Complicating it further is how to count the U's. Especially now, as the stupid law allowing U's to vote in party primaries means many true D's and R's and now registering as U's.  You simply cannot assume that most U's are in the middle anymore.