Oh, this is a tough choice. I have a 66 and a 27 (which we all know is identical to the 28 except for the finish and a few other touches). I go back and forth concerning which I prefer. I carry neither of them but they both see a lot of range time. My 66, being lighter, points a little more easily than my 27 and is just a bit more comfortable at arm's length. But, the 27, being solid as a tank, really soaks up the recoil. Both guns are extremely accurate.
I wouldn't know what to do if I had to choose between 'em. Currently, I'm firing magnums exclusively from the 27 (158 gr) and firing mainly 38 +Ps from my 66 with an occasional cylinder of magnum rounds thrown in for the fun of it. I'd say that the heavier gun is a better choice for a steady diet of magnum rounds. If, on the other hand, you intend to fire mainly 38s or 38 +Ps, then, you might appreciate the relative lightness of the 66.