I often run 2 compressors - one after envelope filter types but before the drive, and then after the drive as well.
If I have to only have it in once place then I'll lose the after drive one.
Placement causes very different sounds and there is no right or wrong place as long as it works for you.
I love my Empress Compressor, but I'm very keen to try the new Keeley one as well - that looks like a great unit.