I've got a few pairs of various Magnums, but haven't worn any of them for airsoft. They just seem too flimsy, lacking decent ankle support and I question their ability to keep water out, despite being Gore-Tex. Thankfully I didn't have to pay for them.
At the moment I wear Haix hi-legs, which are well broken in, very comfortable and great for keeping your feet dry. However, they are becoming pretty work down on the sole, so I'm actually going to have to part with cash for a replacement. Looking at Lowa, Altberg and Salomons at the moment.
As @Lozartsays, most important thing is actually trying them on before buying, and don't underestimate the worth of a decent pair of natural-fibre socks.