I have both of them and love them. Here is what I did:
4-16 is used on my 7WSM for my LRH out to 500-600 (which is LRH for me, and being on the east coast its hard to find spots just to reach those distances). While paper punching I would like more and was thinking of changing, but then last year I shot a deer at 450 and at 16 it was more than enough so I'm just leaving it.
6-24 is used on my 6x47 Lapua. This is a designated varmint only rig and so I wanted the higher magnification in order to see prairie dogs at extended distances. I built the rifle and then wound up deploying again so I've yet to do anything but take it to a range twice.
That's just what I did and I'm happy with my choices. If I ever decide to extend my range to over 600 I may change, but for my limitations right now I'm happy