FTP!
With a better client if you need to - I wouldn't put (heee) my bet on some dinky consumer app but there's going to be some good one, or if all else fails Android is Linux and there's probably a build of some proven command line client...
Or external drive (pretty much the same comments apply, especially if using an unrooted phone and having to go through the Android SAF "please select the root of the device and press ok")
Drivedroid can make your phone (assuming it's compatible) emulate a flash drive, but getting files into a disk image is not particularly convenient either!
tl;dr - get a real PC and improve your satisfaction quick