I currently am using SizeUp which is really nice to use, but I don't want to pay for it.
I started looking for a FOSS alternative, Spectacle caught my focus.
It has far more control then SizeUp and I really like it, however it is missing that one key feature.
SizeUp has by default ⌃⌥⌘/ which snaps the window back to what it was before moving it around. It's quite useful.
Second and final suggestion, would it be possible to remember (relative) positions over monitors? Such that I put the window to the far left 1/2, when I move the window to the other monitor, it's still on the far left 1/2.
Spectacle allows you to undo window movements; the default hot key is Option + Command + Z. Does that help?
Something like https://cordlessdog.com/stay/ might help you.