JGs aren't bad.
Unless you try to upgrade them... I haven't heard of anyone doing a hassle-free upgrade.
Their Sig552 is a very decent gun.... worked great for me... shot pretty hot, was very accurate, and under $110.
That is, until I opened the gearbox... it's taken me almost 2 months to get it firing again. lol.
Also... Look at the Echo 1 G36's. Cheap, very reliable, very sturdy, and pretty good (fps is low, but still very accurate). Also, JG's and Echo 1 both come with batteries, so that's definitely a plus IMO.