My vote is for the speck. I have trouble holding on to phones (small hands) and the extra grip is super helpful. I drove 2 hours today trying to find this case in stores. Nobody seems to have it yet.
I have the Spigen Rugged Armor and the Speck Presidio. To me they are completely different cases. The Spigen is nice, slim and on the slick side. When using the phone, it has a nice look to it.
The Speck is very grippy with the grooves on the back, a little more bulk to it, and the front lip isn't quite as "refined" as the Spigen.
For me, the Speck is back in the packaging and the Spigen will stay on the phone.