i have both planet bike and SKS, and honestly, i like them both. the SKS fenders tend to wobble less, but the stay hardware is heavier. so i call it a wash.
for anyone who has the planet bike fenders with those tiny (and pointless) mudflaps, you can upgrade to nice long ones. planet bike sells the long versions on their website for $5/pair. they're the same nice ones that come with their cascadia line of fenders, but will fit perfectly on the hardcore models as well.
or, you could just go the DIY route and glue on a piece of stiffener plastic, as i did on my planet bike 20" fender:
