Take a look at Specna Arms, CYMA Platinum, Saigo and other similar brands that have decent internals and externals and some or most of the bells and whistles you want in a modern rif.
Marui launched their MWS system some years ago and it's a robust and stable platform, if you are into GBBs. The system has already been copied by CYMA and Double Bell, so there are cheaper alternatives as well.
Green gas is still green gas, there are way more electronic solutions around, but other than that it's the same hobby. Enjoy