Hi! First off before I start the guide I just want to tell you that I have been airsofting for more than 15 years and I basically had almost every airsoft make and model come & go through my hands and this guide is based from my experiences as an airsofter. Here's a quick Pro's and Cons on brands that I have owned and encountered through the years and I am also familiar with the inner workings of airsoft guns (cause I fix and upgrade them too!). Lets get started!

TOKYO MARUI

PROS:

-Great fitting of parts and their tolerances are very close from gun to gun (basically if you buy 2 Mp5's of the same model and compare them side by side almost no diffence)

-Amazing consistency of quaity control from every gun (I do mean amazing! from the ouside detail up to the gearbox and inside the gearbox the best I have seen)

-Stock gearbox parts are very well built contrary to popular belief. (1 example are the gears. I have tested and confirmed this myself  that it is able to hold a PDI 190% spring with no problems (considering that you have shimmed it right) and I have shot more than 8000+ rounds through it and this is also in conjunction with the stock marui piston.

-Measurements inside the gearbox are exact (like the holes for the bushings ect..) and the gearbox shell itself is very strong.

-Tons of models to choose from and they are the pioneers of AEG's

-For its high quality it has a very reasonable price

- A lot of parts makers develop parts for their guns fitting of parts from other manufactures requires little and most of the time NO modifications to the product or the gun itself

-High third party manufacturer support

CONS:

-Bodies are mostly made of plastic but as seen above there's alot of manufacturers that produce after market part for their guns. Also they dont use cheap plastics and the individual finish make it look like the real thing and on some guns they actually incorporate a lot of metal parts!

-Hard to import w/ trademrarks because it is not licensed

-They do not produce a lot upgrade parts for their own guns and therefore rely on third party manufacturers to produce for them

CLASSSIC ARMY

PROS:

-All of their electric gun line-up have metal bodies installed

-Licensed trademarks specially on their armalite models

-Although they copy alot of  Tokyo Marui models. They broke that cycle when they started to produce their M249 series and the CA 33E

-They also produce upgrade parts both internal and external unlike Tokyo Marui

-Pre-upgraded spring installed

-Comes w/ 1 hicap

CONS:

-The quality of metal used in their guns is pot or "pig" metal which isnt very strong and based on my experience I actually saw it crack and break on my friends CA33E. They have claimed to have solved this problem with their newer models but I have yet to see it.

-Fitting of external parts from other manufacturers almost always requires modifications unless it is made by classic army itself

-The gearbox itself  has problems with measurements and I noticed that the gearbox shell flexes over time specially if your running it with an upgraded spring and if you dont remedy this by shimming it from time to time it can really cause catastrophic failures. Good thing that there are tons of third party manufacturers who produces gearboxes but then again I cannot guarantee the fitting on their bodies.

-A little on the expensive side

-The QC is horrible

ICS/OLYMPIC ARMS

PROS:

-All of their AEG line-up have metal bodies installed

-Fully licensed trademarks from Olympic Arms on their AR models

-2 piece gearbox like the one offered by systema and ICS produce it for their AR models and on some AK models

-Quality and built of the metal body is better than classic army's

-Like systema it is very easy to upgrade the spring

-On their AR models they have incorporated a spring release on the forward assist button

-Pre-upgraded spring installed

-comes w/ 1 hicap

CONS:

-The bushings are nylon plastic?!?

-Unlike systema overtime they develop alot of problems with aligning the 2 piece gearbox which in turn causes piston and gear strippage as well as gearbox siezures. Again this can be solved by buying a new  a 1 piece gearbox but fitting is questionable.

-They immediately start having problems with 400+ fps springs

-Kind of expensive

-Product selection is only limited to MP5's, M16/M4's and AK's

SYSTEMA

PROS:

-If you want realism this is the model to get!

-Very easy to upgrade

-perfected the 2 piece gearbox design which makes field stripping like the real thing

-Metal body is present in every model

-Able to take real steel parts with little or no problems

-High quality materials used

-They manufacture their own upgrade parts

CONS:

-VERY EXPENSIVE!!! (I just needed to stress this!) The cheapest one I saw starts from $1400+ upwards

-Models are only limited to M16/M4's

UTG/ SRC/ AIM -Although they are different menufacturers I chose to classify them together becuase they are almost mostly copies of Marui. I have never owned the SRC or AIM but have owned a UTG gun and I had friends owned SRC and AIM. People claim them to be direct copies of Marui but in fact they are not.

PROS:

-Very cheap!

-Parts are interchangeable between Marui AEG's

-They always come in complete packages like they include scope mounts, hi-caps, batteries and even a charger!

-SRC offers AEG's with full metal body upgrades as well as crane stocks for their M4's

CONS:

-They are mostly plastic and if not all plastic and compared to marui, they use more plastic and the quality of plastic they use is low quality as well as the finish

-Bought a UTG MP5, siezed after 5 minutes of use, because the fit of internal parts are horrible and seams are highly visible as well as imperfections of internal parts like gears, hop-up, piston ect... Again there are aftermarket gearboxes but the money your spending for it why not just buy a reliable Marui?

-Limited to mostly to M4's except for UTG which also produces AK,s and MP5's

-QC is the worst

G&P

PROS:

-They have the best looking M4 AEG's in the market

-All their AEG's have metal bodies installed

-Level of detail is very high as well as the quality of parts used

-They are one of the leading AEG parts manufacturer so product support for their own guns is no problem

CONS:

-They are more expensive than ICS and Classic Army

-No matter how good the gun looks there are still some quirks with their gearboxes compared to Marui's but then again you can directly bolt on a complete Marui gearbox in them without fitting problems!

-They are only limited to M4 models

TOP 

PROS:

-They are the pioneers of the M60/M249 AEG's

-Able to empty their entire 1200 round resevoir in one trigger pull!

-Makes a very distinct sound when firing (altough this could also be considered as a con)

-Mostly metal

-Very easy to load

CONS:

-Big and Heavy (well its an M60/M249 what do you expect!? But I think its a pro)

-There are flaws in the design like the older M60 models start having problems at around 10-20k rounds and and the E3's which is a little better at around 50-80k rounds

-Upgrades are hard to source as well as expensive

-Has the most complex gearbox design and is very complicated to upgrade

-Some of the metal parts are low quality and breaks easily

-QC is somwhere in between ok to horrible

-expensive but I think price is kinda justified if not for reliability issuses

Anyway I am stopping from here there are a few more brands to mention but I never owned or examined them yet. Also I just want to stress again that this guide is based off my own experiences, research and observations and nothing is embellished. Hope this guide helps you on you next purchase. Thanks for looking! God bless.