Guys forget about the maintenance and what not, for both systems are people on this forum that can fix it.
Lets talk about your gaming experience,
GBBRs have limited ammo, your looking at nothing over 50RDS. afaik
AEGS, They got hi caps, mid caps, and low caps. as a newer player you'll find yourself using a lot more ammo, I know I did, I saw someone move and I emptied an entire magazine