i agree with fred, no lock guns ever, my picks would be,pre lock 342 or 642, model 66 4 inch, model 625 in 45 acp.
He said NEWER guns. Otherwise, I'd agree on the M-66 and add a Model 60-7 and a M-60-4. And, I'd sorely miss an M-686 made before they drilled the top strap for a scope mount.
"newer" guns meaning w/lock?
I'd say: 442, 4" 686, and a 6" 629
"Newer"? Ruger SP-101, 3-inch bbl, Ruger GP-100, four-inch bbl., and the discontinued GP- 100 with six-inch half lug bbl.
No MIM parts, no lock, and great ruggedness and reliability.
Reasonable prices usually, too. Also great versatility. (All in .357.)
Might skip the six-inch and get two of one of the others.
I don't even consider current S&W handguns. To be sure, some here don't share that opinion. But I'm not answering on their behalf.
T-Star