I can't speak to other brands, but may as well steer clear of Aukey in my opinion if looking specifically for QC2.0 on the G4. I've had two of their car chargers now (having replaced the original under warranty), and in both cases the QC2.0 has been too finicky. Even with the screen off it sometimes wouldn't charge well. It's a dual port with one QC2.0 and one standard. I find I get more reliable, and often faster charging off the standard port.
Like others said, even when the QC2.0 is working, it's not much faster than the OEM stock charger. I don't think it's really worth the extra expense for a QC2.0 charger for the G4. I just happen to have it already for my M8, which benefited big time from it.