GBBR mags are pricey, WE mags (used / M4) go for around $20-25 each from my experience, which is cheap, versus a used GHK mag which is around 40-60 each.
Anyways, that aside, GBBR are "more realistic" but also suffer from consistency and cooldown issues.
AEGs are better for beginners, and you can hold 50-2000 rounds, versus a 30-40 round mag from a GBBR.
I always advise going AEG first
You can look up KWA "ERG" which have a small amount of recoil, and a "stop on empty function" (aka gimmick bolt lock).