I've recently been in the same boat.
I went for a G&G CM18. It was £165 from Zero One and for the money, I'm very happy with it.
It is quite plasticky, but the build is solid. Only wobble is from the stock, and that is only slight.
Shoots really well, good rate of fire and range is nice too.
And it looks different to the CM16 and Raiders that most tend to get - the two tone Black/Tan is nice.
Not sure how accepting of LiPo batteries it'd be though. I've got Nimhs.