I've asked around on this topic a bunch. No clear consensus. Drove a std t56 w the Pro 5.0 and liked it. Supposedly the Magnum has a upgraded, nice shift feel to it so I'm going to try that first...
McLeod/Red Roberts have the Slik-Stik - I'm considering it because of the many offset shifter position options for my 66 Nova. There in Placentia (SoCal) I believe. Thought I'd go by and check them out. What little feedback I've gotten was positive.
MGW. Its tight and a bit of work to shift (as it should be), but the best thing since sliced bread. Had them in all my cars after running the gambit of shifters. I've got one in my 67 w/ T56 now.