I have a 6" 66, a 5" half-lug 686+, and a 5" Jerry Miculek PC627 V-Comp. That's a K, L, and N frame and 6, 7, and 8-shooter respectively. The 66 & 686+ have HiViz sights - and were my first two .38/.357M steel plate challenge revolvers. The gold beaded Patridge front sight made the 627 the slowest to aim of my revolvers, so I went back to the 686+. I would suppose that it and the 6" 66 'point' a bit better because the 627 is muzzle heavy with it's full lug and muzzle-mounted compensator or muzzle blank - either of which is something else to clean.
While all three have the same lockwork, the PC 627 has better fitting - resulting in a better feeling trigger. A trip to the PC shop for a 686/686+ would equalize that somewhat. The 66 uses the HKS #10 speedloader, while the 686+ uses the #587. The 627 employs tempermental and flimsy moonclips for .357M's which will accept 'some' cases - mainly Remington's or Starline's, in my experience (It thankfully functions fine without the moon clips!).
Which would I keep if I could only have one? No doubt, the PC 627. No doubt the others are more fun - and get shot more nowadays - the 627 is harder to clean and that 8-round capacity wears off. But... the 627 used is worth more than the price of a new 686+ AND the cost of a trip to the PC shop. Of course, I would likely consider a 620 first - as it is just a 4" 686+ with a partial lug - much more to my likes than the full lugs of the standard 686's and 627. Now, if you are a man of means, get a new PC 627 without the comp - and with the tapered lug - that would be real nice.
Stainz