[kullwarrior]

Daytonagun, once you go there you will never return to the world of internal mag GBBR (or propane mag)
Available in:
AK74 Variant
AK47 Variant
Type 56
M4
M16
M110
hk416

I've fired
G&P WOC, Prime GBB, KJW M4, WE SCAR, and of course my DG AKS74U

Of those the recoil can be best describe as followed:

1) First few shot
Daytonagun has the most power
then Magna system Prime GBB, WOC
KJW M4,
and lowest with SCAR

2) After 10 rounds
Daytona, no cool down
KJW
Magna
WE

In general:
GBB are PITA in terms of reliability and cost. I've spent probably around $3000 on the GBBR before giving up and realize its a dead route. The Magazine are too fragile to do any tac reload, as they're heavy and easily leak (if you chuck em around every mag will even Pro-Win)
Parts will wear out, WE seems to be the fastest and then WOC, Prime. KJW its ok, but at the same time not as realistic.

I'm not gonna mention AGM because its literally the shit of shit of shit. It's cheaper to build a more reliable one from parts and G&P receiver.