Based on that, I'd go with the .357... Ruger I assume?
The GP100 was my first centerfire Restricted
Semi:
-Most parts can be easily swapped/stripped; barrel changes are easy.
-Loading mags is more fun as well as quicker if you have multiple magazines.
-LCF (look cool factor) is high.
-Picking up brass sucks
-More chances of failure
Revolver:
-Ultra Reliable
-No brass policing
-Powerful
-Barrel is not changed easily
-Canadian law says that the barrel does not include the chamber so we get lots of ugly Revolvers here of the 6" type.
Sorry but revolvers are not more reliable than an auto.
Here's a nice overview for those on the fence.
Revolvers

Limited magazine capacity

Heavier than most autos,
larger in overall dimensions than autos

As many parts as some autos and more parts than others

Most parts require a gunsmith to install, no "drop in" capability

Increased recoil due to magnum cartridges

Long and heavy double action triggers

Many moving parts when trigger is pulled

No manual safety

No "out of ammo" indicator

Many revolvers have integral rear sights. 

Many revolvers have no option for night sights

Cylinder gap blast can be quite severe

Timing issues
Blown primers cause firearm to fail indefinitely

Aligning six rounds with six holes requires fine motor skills and more effort than aligning one large magazine with one large hole
Cannot execute tactical reloads(top ups) with speed loaders.

Cannot execute tactical or emergency reloads without rendering the firearm useless

Partial reloads(less than full cylinder) can result in dropping the hammer on several empty chambers before the live rounds.
Cylinder gap blast destroys the top strap, eventually rendering the firearm unsafe

No ability to mount a light

Slower reloads

Failure for any ONE casing to fall from the cylinder renders a speed loader useless until all chambers are cleared.

Spare ammo(speed loaders) take up more real estate than magazines with fewer rounds

Unable to surpress a revolver

Ejector rods back off causing the cylinder to lock up

Excessive firing and heat build up cause empty cases to stick in the cylinder

Excessive firing creates large deposits of carbon on and in the cylinder

High bore axis and magnum calibres combine to form a turning moment, increased muzzle flip.

Open action prone to debris

Slow follow up shots

Difficult to operate one handed



As far as accuracy goes. A single action trigger is a nice advantage for precision shooting. From a practical stand point, the revolver shooter will never #### the hammer when using the firearm in a high stress situation. Sight radius is neither critical nor required for accurate fire out to and including 25 yards. Proper training and practice can hone a persons ability to shoot naturally, also known as instinct or point shooting to the point where sights are neither needed nor depended on. The length of a handguns sight radius varies so little from handgun to handgun that the difference is a non issue. Handguns are designed for close range and usually sport large chunky sights which reflect their intended usage. They're handy/convenient, and quick to bare. They are not precision instruments from a traditional precision stand point. As for operation, the slide does not begin its movement until AFTER the projectile has left the barrel. Slide movement as a cause for "inaccuracy" is usually a result of poor sight picture or operator error. 
Some other points. Barrels and their lengths can be changed on a revolver, at the cost of other attributes, Namely weight and handling characteristics. Barrel length has very little to do with accuracy, Velocity is the key. An increase in barrel length can increase velocities which results in more consistent accuracy over greater distances. Again, handguns are designed for short range work, making an increase in velocity/accuracy of little gain. Even with an increase in velocity with a longer barrel, revolvers are still wasting much of their potential gain due to the cylinder gap.
 Revolvers have 6(or more) open chambers for which debris can enter and cause problems. A plugged chamber could very well cause the revolver to detonate on firing. For most autos the only access points are the mag well and the muzzle. Beretta being one of the exceptions with its open slide design.

Revolvers are not necessarily easier to train novices on. Both autos and revolvers require three movements to operate. Insert magazine/shells, Cycle the slide/close the cylinder, pull the trigger. Many autos have manual safeties which may require operation. Revolvers require the shooter to mind the cylinder gap so as not to get burnt or get a gas cut. Other than crossing ones thumbs, the slide will not damage the shooter if they run their fingers against the slide during firing. With rapid heat build up on revolvers from sustained firing, the shooter must make contact with a potentially hot cylinder. This is not required by those who shoot autos. The slide does not heat up as rapidly, nor does it achieve the high temps a revolver can. Should the auto get extremely hot, the slide release can be used as an alternative.

There's probably some more points I've missed but I'm sure you get the idea. Most military's and LE agencies issue autos. The domination of autos over revolvers in both of these areas was not achieved by the offering of cheaper firearms or inferior firearms.
TDC
ETA: Some of the points above are in reference to duty/service pistols but the same principles apply to competitive shooting as well.