I use a Model 14-3 for ICORE.

After shoot many other 6 inch guns, the 14 has the best action/trigger of the group. A competent gunsmith can tune a 686 or 19 or 66 and make it sing.

But a Model 14 get you there out of the box.

The guys in my ICORE league shoot a variety of guns, but the few of us who shoot Classic (unmodified 6 shot, no moon clips, speed loaders only), shoot either a 14 or a 19. But the guy shooting the 19 like mine enough to by a 14.