There is also the Maintenance aspect to take in consideration; They're both different beast in that regard
In the end, it all boils down to personal preference though, IMHO.
AEGs require much less frequent maintenance, and once tuned correctly it can last a considerable amount of time without you having to fiddle with it. Getting it tuned properly is where it hurts I though
GBBRs are closer to real steel when it comes to maintenance; It's a good habit to clean them after a game, re-grease them before (or some variation of this). Most GBBRs have pot metal (Usually Zinc Aluminium, as with many AEGs as well but they suffer less stress) parts that under stress will be likely to break, so you have to eventually replace a few parts. People usually replace them with Steel equivalent. Once done, they should last a very good time, unless you don't take proper care in maintaining your gun.
Most GBBRs can be fitted with an NPAS or similar device, which allows you to change the gas output, thus the velocity of your projectile. This way, you can use the same gun at different fields limit. Some AEGs have a gearbox with "quick change" springs, which permits the same, but they are a bit rarer, I think.
AEG magazines range from 30 to 3-500 rounds in capacity, and cost from a few bucks to a few tens of $ each. They're just a shell with a spring that push the BBs upwards.
GBBRs magazines also serves as gas tank. The reservoir taking most of the space, mags are limited to "Real Cap" (same capacity of their real firearm equivalent) or close to (30-40 rounds). They are much more expansive because of this, ranging from 30$ to 60$ for the typical magazines. Having less rounds, you have to buy more of them too. Some of the most popular brands tends to develop gas leaks, so mags needs to be cared for too when issues of this kind arrives.
I've played airsoft for 2 seasons only now, and had both kind at the same time. I now decided to trade my AEG for a GBBR, as I prefer these for many reasons. Someone else would probably tell you a completely different story. If you can loan one and the other a few games for you to try, you'll get a better idea of what you might prefer; but you'd need to actually "play" *in* the gun to really understand the diff in my opinion
Originally Posted by Brian McIlmoyle
Real life comparison,
GBBR- bang bang -- Giggle
AEG-- merrrzip merrzip -- meh