Unless you have pretty small hands, the G9X won't allow very much of a palm grip. It's really best for fingertip or claw, but you can probably adjust to that. The smoother grip will probably be more comfortable to you at first, but you can just try both if you get it. I used the slimmer, rougher grip for a while, but I just switched to the wider, smooth grip, because it makes my hand cramp up less. That's mainly because I play more FPS multiplayer these days which changed the way I use the mouse (as opposed to RTS or RPG). That's all personal, though.
What are you looking for in a mouse? I got a Deathadder Black a week or so ago, and I think it's great for palm grippers. I'm getting a Corsair M60 and Spawn today, but the latter is definitely a small, claw-grip mouse. So, it's all in what specs and shape you're looking for. The other mouse I'm looking at is a Zowie AM. It's highly recommended.