Get the sintered or semi metallic ones, I've just been through a pair of organic pads and they weren't any grippier. Just squealed horribly and wore out after three weeks. I've got some Jagwire semi metallic now which are very good, quiet and powerful braking.
I've got sintered ones on the way. Even the worst disc brakes are probably more powerful than my old rim brakes so not too concerned about much other than longevity.
Why sintered? What's the diff. between organic, kevlar, sintered, semi-metal, etc?
Can get a set of 4 for £18. Is there a cost/quality trade-off with pads I should know about?