Honestly, I wouldn't go for either the m14 or ebr in GBB. Magazines hold 20 BBs, are expensive as all get out, and require a good bit of time to reload. Try out a JG M14 (cheap used) amid see if you even like the set up. The safety is in a good location, but reloading takes practice and switching from semi to full auto takes the shooting hand off the grip. Not exactly the most user friendly set up.
Btw, rails are overrated. Try shooting iron sights for a bit. It does wonders in CQB.