Which is better a medium rod or a light rod for ned rigs?

Some will say medium - some will say medium-light.

I go even lighter - a Procyon Light/Fast, 1/16-3/8 lure rating, 4#-10# line rating - I run 20# Smackdown with 6# Siege leader.

Depends on the weight of the jighead you like to throw.  Generally a rod rated 1/16-3/8 which is typically a ML.  

I use a medium light exclusively for neds. Tried medium and it was too stout...tried a light -too soft. So I went in the middle.

My mediums are too much for Neds.  I use my medium lights.

Most consider lighter powers better for Neds since the Neds are pretty light and the lighter power rods will load better for better casting.  Find a rod which has a lure weight recommendation that includes the weight of the Neds you plan to use.  Longer is better for longer casts if that is important.  I like 7 foot.  

Ned rigs are my bread and butter and I've used a variety of rods with the presentation.  It comes down to light or medium light.  I see some guys use a medium action rod for Neds and I know they are missing some of the most sensitive bites.  If you are getting a Ned-dedicated rod and you use 1/16th and a TRD the majority of the time, go with a light action rod.  Sensitivity and casting distance will be enhanced with the light action.  If you are using 1/10th or heavier the majority of the time then I'd go with a medium light action.  The medium light is much more versatile and you can use it for most finesse applications besides Neds.  Personally, I rarely ever use heavier than 1/10th.  My general rule of thumb is 1/16th in shallow water and 1/10th in deeper water or if it is a little breezy.  

 

In terms of rod, the longer the better.  I absolutely love my 761 Steez for Neds but that rod is over $500.  Before getting that rod, I used a 7'4 light and medium light action Dobyns Champion HP.  I've kinda gotten away from Dobyns so I would not get those rods today but they definitely did the job for me.  I'd look very closely at the 7'6 Tatula Elite If I was wanted something more reasonably-priced.  Good luck.