Gatorskins, spare tube and patch kit. I tried Slime once and it was an awful, messy failure. I cycle thousands of (road) miles a year in goathead country (Colorado and Arizona) and one a year on average gets through. Sometimes I hit a patch of them, pull out dozens, no flat. Sometimes a slow leak. Wires from radial tires get through about as often.
I love those Gatorskins. And they're easy to handle (mine are wire bead). Front flats take five minutes, rears take seven. Road Morph pump helps a lot.
Negative on replacing a patch. I've tried it a couple of times.