I've always been a plain slate or aluminum guy. I've had MAD, Zink, and Woodhaven slates, but none of them made me really want to use them. I just had them for a "different" sound in the vest. I Since have tried Halloran's Crystal Mistress, Twisted Sister, and Southland's Sadler McGraw Elite Crystal. Although, I loved the Twisted Sister, I chose the Southland. Just something about it made me WANT to use it and it will be my first choice for friction coming out of the vest this year. I'll definately own a Twisted Sister in the future, but the Southland Elite Crystal is the best I've tried yet. It sounds great and just "feels" right in my hand.
BTW...I know it's not a "crystal" surface, but I've got to give a shout out to the Hook's bronze glass...super sounding call.