I can only comment on mine, a cyma krinkov. Got it second hand from here for 140 i think with 5 mags I love it, but I don't use it a lot. Good rate of fire, a bit noisy but accurate. It's 7.4v, and takes thin stick batteries which are less common and don't fit my other rifs. I'm told it can run on 11.4v but never tried it. One battery will last a morning, but not a full day. Seems to like .25s or .28 BBS.
The few who have borrowed it like it, but the kids find it a bit heavy. It's had a steel barrel and an upgraded bucking. I've never opened it up, as its never me down. One day I'd like the wooden pistol grip to match.
Few lads at the site I use have the plastic AKs, and they seem to rate mine higher.
Not sure if that's any help mate.