Boxes analyzed for outdoor durability.
Here you can see that the RS DA-5200 has a pointed topside and rounded sides for horizontal mounting, which would seem to be well suited for shedding water, avoiding water puddles which may leak into the plastic seam and also possible ice damage, which would weaken the plastic seams or crack/seperate them, thus increasing the likelyhood of water damage/corrosion of the internal amplifier and antenna elements.
The Philips has lips which may tend to direct water onto the top and keep it there, especially asking for ice prying it apart and water puddles....however you could angle it with its mount to help prevent this. Additionally, this unit may perform best mounted horizontally, and it conveniently also has a pointed edge on one side to shed water. The Philips may use slightly heavier gauge plastic for its antenna box plus good engineering as it is strong and resists flexing.
The GE has a flat top and rounded sides. However the ability of its gooseneck mount to resist weathering is suspect.
I put these units in this order for Weather Resistance.
1. Philips MANT940
2. RS DA-5200
3. GE Futura Outdoor