Haven't installed any but the here's a few pros and cons for each.
over the door frame
-easy to install
-a bit better at blocking water intrusion because it goes over the window
-no window contact
-may leave behind tape gunk when you try to take it off and it may be hard to remove
-more prominent than snap in
snap-in
-looks smooth
-easy to remove and no adhesive is needed
-they're designed to be really snug so you may break the deflector if you aren't careful while installing it
-may loosen over time
-It does touch the top of your window possibly scratching it but shouldn't be a concern if installed properly and cleaned here and there
The pros and cons are negligible, at least to me, so it's mostly down to looks and how much effort you're willing to put into it's installation.
over the door frame
-easy to install
-a bit better at blocking water intrusion because it goes over the window
-no window contact
-may leave behind tape gunk when you try to take it off and it may be hard to remove
-more prominent than snap in
snap-in
-looks smooth
-easy to remove and no adhesive is needed
-they're designed to be really snug so you may break the deflector if you aren't careful while installing it
-may loosen over time
-It does touch the top of your window possibly scratching it but shouldn't be a concern if installed properly and cleaned here and there
The pros and cons are negligible, at least to me, so it's mostly down to looks and how much effort you're willing to put into it's installation.