I know what you mean, it took me awhile to find something decent. But there are a few easy things you can do to spice of the stock sounds. Drag one of the stock pads into Ableton, then go to audio effects then drag and drop the stock Auto filter into the instrument rack for that instrument. Then play a note and adjust that filter until you are happy with the sound. That alone will work wonders. Then from there you can add chorus, delay, and anything else you can think of...Hope this helps!
You might be able to get some good ideas on how to build pads from Will Dogget's video at the link below. He is using Suite, but much of the sound he's getting is done with effects. I would say just experiment with it.