USGI > most all commercial copies. Even if the barrels is import stamped.
Avoid 30rd mags. Stick with USGI 15 rounders. USGI 30's are OK....but there are too many fakes, and real USGI 30's go for stupid money. Some non USGI 15's are decent. The KCI Korean ones work.
If you want a shooter, look for one with the post WW2 upgrades....IE adj. rear sight, bayonet lug barrel band, low wood or M2 stocks. Early featured WW2 guns are very high priced, and restorations festooned with fake parts are rampant.
Inland, Winchester, Underwood, IBM, Rock-Ola, Standard Products, Saginaw, Saginaw S'G' (Grand Rapids plant) Quality Hardware, National Postal Meter, and Irwin Pedersen are the ONLY USGI MFG's. All produced during WW2. IMHO, Stick with looking for an Inland, Winchester, or Underwood....they are #1, 2, and 3 in most produced, and other than a premium for the Winchester name, should be the easiest to find. That being said, if you find any of the other MFG's for a good price, buy it. They are all GTG.
Never EVER buy a chrome lined USGI replacement Herlo barrel. They are junk. Rejected by the Gov. because they were short chambered, and the chrome chambers can't be reamed (easily) as well as other problems like chrome flaking, poor overall quality, etc...If you come across a carbine with one of these barrel, walk away.
There are a few commercial copies that are good. Fulton Armory, and James River Armory's "Rock-Ola" marked carbines are top notch and as good as USGI, they are built on forged mil-spec receivers, use Criterion barrels, and use quality USGI or new made parts/wood. However they are more $$$ than decent USGI examples, but they are "New" if that matters to you. Stay away from the new Inlands, Auto Ord, and ALL the old Universal's. They all have problems. Some of the other old comm. carbine can be good, but it's a crap shoot.