The Nuprol defender is a poor choice.
It uses a microswitch, and whilst that can be a great feature, it does it without a mosfet. You have to have a mosfet to protect the switch. Without one your little microswitch is a ticking bomb. It's not a case of if it fails, but when.
If you have a fet fitted to a nuprol then it might make the gun reasonable.
If you want something different go with specna arms.
For similar money, to the G&G you can get one of the SA-C03 CORE guns. Rotary hop, 6.03 barrel, Well thought out gearbox internals (Bearings, Full rack, Steel gears, Standard contacts), QC spring, Silver wire, and metal rail with covers.
In comparison the G&G that comes with a dial hop, 6.08 barrel, Decent gearbox with equally good internals, Plastic Ris and no covers. Sights.
It's a close call between them but the addition of the better hop and barrel mean it has the potential to save you some pennies on future upgrades.
https://gunfire.com/en/products/rra-sa-c03-core-tm-carbine-replica-half-tan-1152223001.html
The 04 has an English description as well. The model differences in the 03 and 04 are the barrel lengths. (Both come with the grip).
https://gunfire.com/en/products/sa-c04-core-tm-carbine-replica-half-tan-1152215723.html