Resin/organic brakes pads should be used on most bikes that don't do any hardcore trails, downhills, or enduro races. They bite hard and grab really well, but if you're hard on them they will heat up and start to lose their effectiveness. Then you just need to let them cool down for a bit before riding on them.
Metallic brakes grab good since the won't heat up, but you'll need new discs for them since they'll eat through them faster, and you're going to have trumpet brakes all the time, and that can get annoying real quick. Plus you'll get the "wtf is wrong with your bike" looks from people who don't know any better.
I agree the brakes on the Wallke aren't that great and it feels like the pads are going to warp the discs. I think the main issue are the crappy Tektro brakes that comes on the X3 bikes, as they're some bottom-of-the-barrel single piston brakes. If you get some 2 or even 4 piston hydraulic brakes, then you'll notice a bigger difference in braking performance.
