The basic set up is about what Jim said. Pros and cons across the board.
Rifles the most common barrel leength is 20in followed by 24in than the rest
Winchester 92's or rossi clone PROS about the least expensive, light weight, very strong action, a real plus if you think you might take it hunting (thank you JMB) reliable. CONS rough out of the box, can be real sensitive to ammo length,and D/T the angle feed can jam because of ammo. not as fast as some others, if you get real good you can outrun it. This is the action that is the hardest to work on in the cowboy game, it can be a real PIA to take apart and put back together.
winchester 66 & 73 basicly the same action the 66 being the brass frame and the 73 steel. PROS these are generally considered to be the fastest rifles in cowboy especially after some action work they can be as smooth as ball bearings on glass, combined with a short stroke its hard to beat, simple action easy to work on, is highly favored by the black powder shooters for this reason. Lifter action much less likeley to jam on you. CONS can cost up to twice as much as a 92, they are heavy, the action is not as strong as the others, though generally this is meaningless with cowboy loads.
Marlin PROS this is a strong fairly simple action has a side eject so you won't end up with brass sitting in your hat can be about as fast as the 73's CONS not quite as reliable as the above.
Winchester 94 CONS generally considered the worst of the levers in the game not very smooth, diffacult to to do a lot of work to. This action was designed for real rifle ammo and does not adapt to pistol rounds well. PORS this is usually the least expensive rifle you can get and its a made in the USA real winchester and they aren't making any more.
Colt Lightning and clones. not ready for prime time yet. most all of the makers of these are havint teething problems. PROS ferry cool guns so you get lots of style points, when working right can be very fast CONS lack of reliabilitybut when the manufacturers get them right they should make a good main match gun.
Pistols
Basicly you have Colts & clones and Rugers the rest are not seen a lot till some one really gets into the game and is really shooting for the fun of it. These would be the Schofields, Remingtons, and everything else.
Colt and clones PROS this is the gun you think of when you think cowboy it's been around over 100 years and still works. most people like the grip, a simple proven design. THE cowboy gun Cons it's a 100+ year old design it was never designed to be treated the way we do today, so there can be reliability issues, cost a real Colt is about the most expensive single gun in the sport, the clones range in price from 300 to 1200 bucks.
Ruger PROS built like a tank, one of the strongest pistols in the world. the New Vaquaro is not quiet as strong as the earlier models, out of the box the New Vaquaro is as smooth as most folks need. working on them is very easy, and with the transfer bar system it adds another layer os safety also have the option of a smaller gun the single six in 32H&R mag not making them anymore but can still be found at a reasonable price great for folks with small hands like women and children.CONS they are heaver than the colt style guns and the grips are somewhat bigger more so for the old Vaquaro's but the new ones are still a little bigger than the colt
this is a simple breakdown of the guns you asked about. the best advice is to go to matches let the folks know that you are interested in seeing diffrent guns and cowboys will trip over themselfs handing you guns to try. Try every differnt one you can to see what works best for you befor you put any money into them. But don't worry as you get into the game what you think you need will chang and you'll but more. I know I now have 3 sets of pistols 3 rifles and 4 shotguns
enjoy