Which do you prefer?  As a kid myself and a friend had the American Classic 1377s.  We shot the crap out of them but I remember I seemed to struggle with consistency back then.  I always had better luck with .22 pellet guns in the accuracy and shootabillity dept.  
I've been seeing them at Academy and I'm thinking of picking one up but can't decide on 22 or 177.  What do you all prefer?

Not to make your choice harder but they also make it in 5mm, I think they call it the Blue Streak. But to your point, I have the

.177 caliber because they didn't have any .22 caliber at the time and yes I would like to have one.

Get both. You can buy one, and then buy the breech, bolt, and barrel to have both. Buy the steel breech though. The newer 1377/22's are plastic.  

There are also dozens of mods you can do to these, new valves, pumping mechanisms, seals, etc. You can really bump up the FPS on these with a little work.

Interesting on the 5mm (20cal) as I've never seen one.  My vintage Beeman R1 magnum is in 5mm and I love it.   At this point I'm leaning towards the 22 cal.  I like the .177 simply for the nostalgia aspect of my past but then again I don't remember my old American Classic getting anywhere near 600 fps, I think they were rated around 400 fps and a little faster with steel BBs.

I'm also taking a look at the 2240.  That one is cool also because you don't have to pump!  Co2 is cheap these days.  When I was a kid Co2 made them impractical because of cost and availability of the gas.  Dang it!  I want to get just one as I don't need a tub full of air pistols and I have a good start on that already.

I have both.
The .22 hits much harder.

I went 22 and never looked back. I built one up with an aluminum breech and I ordered one from the Crosman custom shop for my son with a steel breech. I put a pencil to it, pretty sure I was better off ordering the custom model. The only thing it doesn’t have that my self-built gun has is an upgraded valve to hold more air.

The only way I’d go 177 is if I was building a dedicated co2 ratting rig.

I just picked up the 1377 (.177) version in all black. My other pistol/rifles are .177. But, I'm just now going down the rabbit hole of air guns (three in past week). So I can see a .22 in my future.

My 1322 has a 14" barrel, TKO brake, long bolt probe, steel breech, and a 3x9 scope.

It shot a 5 hole group at 45 yards you could cover with a quarter, and it's nearly silent.

I use it to knock down starlings in the back yard- it's so quiet nobody knows. I'm looking into a PCP now, but at the ranges I shoot the 1322 has been great. My only gripe is you can't really get the trigger very light.

Use the Chairgun app to get your pellet drop figured out and you'll be in business!

Take a look at the Diana Chaser pistol. It costs $79 and you get a very nice aluminum breech, adjustable trigger, threaded barrel to install a modulator, hollow hand grip that holds a spare co2 cartridge, and available parts that you can make into the rifle system when you want. Pyramyd Air now carries the parts.

 Some parts off the PCP Stormrider rifle is used for pistol to make into the rifle, like breech, barrel, barrel band, rear sight. The breeches will interchange, but do look different in design and also model name on side. Also, now there's 2 different rifle barrels. One is threaded for modulator(gen2) and other barrel is unthreaded(gen1), but both cost same price of $34. Factory modulator however is not available as aftermarket at this time.

I have the Chaser 22 pistol/rifle kit($129) and with the Micro Sightmark 11mm dovetail sight I use it's a hell of an accurate shooter with either pistol or rifle barrels, and with the factory installed modulator on the rifle barrel, it's super quiet. Modulator is loctited on, but can be removed with a little heat to use on pistol barrel as some guys have  done.

Better

Best

I went 22cal.  No ideal why.  But I'm happy.

2289 backpacker and the new version (plinker?) also come with the support

The 2nd model of the backpacker.  Came with a bug out kit. Has the thinner forend.  I hate it.  
Id like the fatter one.

God this thread brings back sweet memories.  I loved Crosman air guns.  Please refresh my memory; the 13 series, is that the pump action pistols that you can get the rifle stock on?

Years ago there was a guy called "the crooked barn" that would work these guns.  I still have a custom .22 CO2 gun (can't remember the model but it's a crosman) that has a hair trigger and ridiculously long pencil barrel.  He did something also that allows more gas per shot so it is quite powerful.

My 1322 has a 14" barrel, a TKO muzzle brake, an extended bolt probe, and a steel breach and scope. Shoots 14.3 grain pellets 530 fps at 15 pumps.  Just smacked a starling out of a tree- lasered him at 43 yards. DRT.

These 13xx pellet guns are a hoot.

I need to steel breach update my 1377...Can't really put a dot/laser/scope on it without...