OK, let's start with the basics.
The most common small revolvers are the S&W "J-Frames"...these are usually 38Spl (five-shot) but have recently been slightly upgraded to 357Mag (also a five-shot).
In stainless or blue steel they're between 19 and 21 ounces. Various ligher variants exist all the way down to 10.5oz in 38Spl and 12.5oz in 357. Regardless of 38Spl or 357, they eat out of the same speedloaders (similar cylinder dimensions, same "hole pattern").
There are also variants of the same frame size in 32H&RMagnum as a six-shot. These can use the same holsters, and the 32Maggie is a respectable little performer almost on par with the 38Spl.
Many, MANY "functional clones" of the S&W Js exist. The Charter Undercover and various Taurus five-shooters (and 32Mag sixguns) are typical. The Ruger SP101 is a "J-class near-clone" in that it eats from the same speedloaders, but is just a bit bulkier and a LOT tougher than all other snubbies...and also weigh more at 26oz or similar. Still, the SP101 soaks up full-house 357 recoil better than any other snub and it's tougher than most of the S&W larger-size-frame (the "K").
S&W has gone lightweight recently with expensive Scandium/Aluminum alloys, with trace amounts of $6000-a-pound scandium strengthening aluminum. Taurus competes in the lightweight arena mostly with titanium.
The Colt "Dick Special" was a 38Spl (usually) sixgun a bit bigger than the Js. It was finely made and known for accuracy, but had a somewhat finicky action that could go out of time. Aluminum variants: Cobra and Agent. I'm not sure I'd recommend these for the newbie or somebody who wants to shoot a lot.
The next step bigger is the S&W K-Frame sixguns in 38Spl and 357. These are sometimes found in short-barreled formats down to 2", and a few (model 12s) had aluminum frames. (Like all early-model aluminum-frame guns including the Cobra/Agent, 38+P ammo isn't recommended and the "checkout procedure" is particularly critical - if the gun has any "endshake" it will beat itself to death in short order.)
"+P" in 38Spl means about 10% over the standard 38Spl pressure spec, and is hence usually a bit more potent.
So...what to get?
We're currently seeing a revolution in 38+P ammo. New loads by Speer (135grain Gold Dot+P), Cor-Bon (100grain Pow'R'Ball+P) and Bufallo Bore (158grain lead hollowpoint at a bat-outta-hell 1,000fps from a 2" barrel) show a lot of promise (although in some cases more test data would be good). Existing 38+P loads ain't bad even from a 2", such as the Winchester 130grain Supreme, Speer 125Gold Dot +P and the Winchester or Remington 158 lead hollowpoint +P (about 850fps from a 2" barrel). To shoot a lot of these, you want a steel-framed 38Spl of fairly recent make, a late-model "+P rated" lightweight or a true 357-rated gun. Some pieces like early S&W steel guns or the aforementioned Charter Arms Undercover will be OK with a light diet of +Ps (couple cylinders a month or so) and most practice done with standard-pressure target/plinking loads.
A lot of people use good 38+P defensive loads even in 357s, for better controllability and less indoor kaboom. Don't dismiss a good 38 snubbie as a personal defensive weapon.
That said: 357s are hotter, and tougher. If you can handle the higher carry weight, they'll be more controllable.
