So far, the only FCC part that appears superior is the motor. However we haven't seen if one will stack up to a Systema that's properly modded.
Best Airsoft M4: without a doubt Systema PTW
AEG starter: King Arms, but any AEG needs upgrading. King Arns is also by far the best for cost versus build versus depedability. Classic Army, Tokyo Marui, VFC, are acceptable, but they either cost too much, come with plastic bodies, etc.
GBBR: Open Bolt system completely RA tech'd out. I've heard mixed reviews on innokatsu, KWA, etc. I've seen KWA in action though, and it wasn't bad.
If price is no object buy a Systema PTW, hands down. There is no substitute. If it is a problem, start with a King Arms. By the time you dump enough extra cash into it to make it as expensive as a Classic Army or whatever; it'll be a solid, functional, reliable, performer.
Stay away from GBBRs unless your an experienced airsofter, have access to a "good solid" GBBR doctor, and don't mind constant maintenance, frustrating problems, wads of cash in upgrades.
Also note, the "most" realistic feel and weight is also the PTW, they are also more readily compatible with real steel accessories. The most realistic action is he GBBR with a gas bolt.
ďREALITY IS LIKE A STONE. TO MANY ITíS HARD AND COLD, THEY CANíT HUG IT OR EAT IT, IT ONLY FRUSTERATES THEM AND DOESNíT DO THEM MUCH GOOD. TO OTHERS ITíS STRONG AND DEPENDABLE, YOU CAN BUILD WITH IT, BUILD UPON IT, OR WORK WITH IT, ALSO USE IT TO SMASH PEOPLE IN THE FACE.Ē