I have 2 Smith revolvers and 2 Ruger revolvers.
My impressions for Smith:
1. The Model 60 is a superbly accurate snubnose capable of 5-6" groups with .38 Special +P at 150 yards (that's right 150). The gun is small and light, so I would recommend .38 Special +P for target shooting and defense. The trigger stinks. It's very, very smooth and the single action is crisp with no take-up and very little overtravel, but is so heavy. Trigger job will fix that up, but as it's a carry gun for me I don't want any kind of mods for liability reasons.
2. My 686 (which I just bought) is very accurate, 1.5" 5-shot group at 25 yards with el-cheapo Blazer .357 loads (haven't tried any target loads or any of my handloads, and have tried longer distances yet). Has the best trigger I've ever felt on any revolver. The person who owned this revolver before obviously did a trigger job to it. Double-action pull is about 6.5 pounds and butter smooth. Single-action is 1.5 pounds on the money, zero take-up, zero overtravel. Only negative is that it is kind of heavy and polished stainless steel (I prefer blued). It was much cheaper than any Colt available.
My impressions of Rugers:
1. [Edited to add that My impressions of a .44 would probably apply to all Ruger double-action revolver as they are all pretty much the same] My Redhawk .44 Magnum is very strong. Stronger than any revolver out there, except maybe a Blackhawk. The piece is very accurate with a scope, capable of 2" groups at 100 yards. The trigger downright sucked when I first got it. I sent it to a credible gunsmith for a trigger job and it's good, but nowhere even close to comparable to my 686. Kick is relatively mild (for a .44) even with really hot handloads (loads I made up in my more exuberant less experienced days; they actually sprang the bolt on a Winchester rifle and bulged out the chamber, didn't do anything to the Redhawk). Overall strong, accurate, and aesthetically appealing.
2. .357 Blackhawk (which nobody has recommended) is one of the sweetest revolvers I own. The trigger was good when I got it and after I slicked up the action with some careful stoning it became butter smooth. It is superbly accurate with great adjustable sights. Mine is an old pre-saftey crap Blackhawk that is unmodified. Only difference is that I can't carry 6 rounds safely. I'm down to 5, whoopty-shit. I like the 5-shot thing a little better as it evenly goes into a box of ammo.
If you are new to sixguns, the Blackhawk can serve you well. The single-action trigger pull is sweet and it is very accurate. The added benefit is that you have to perform 2 actions before the gun will fire (first cocking the hammer, then squeezing the trigger). Try considering single-actions too. If you must go double-action, the 686 is the sweetest gun available. The Ruger will never have the trigger that a Smith can have no matter what you do to it. The difference between the strengths of actions really doesn't apply to the .357 (I've never seen "Ruger-only" handloads in .357). Frankly, I don't think that there is a difference in strength between the 686 and the Blackhawk, much less any of the double-actions. Also, the appearance of a 686 may be more appealing; that seems really flaky, but it is truly important.