I am not a fan of slime as it breaks down and the fibers ball up after 6months -year. Then you have a "dead rat" balled up in your tube that can't be patched because of the slime liquid. I have heard better things about using Stan's Tubeless stuff in place of slime.
I run Schwalbe tires with kevlar layered in. I have both the Big Apples and Big Bens. They work well and I have not had a flat in a few years. That is saying alot as I live in an area with lots of them. I have also found that riding in the street is much better than riding on sidewalks or vacant lots for goat head avoidance.
Sometimes it seems like those goat heads sprout legs and walk out on all rideable surfaces. Riding in these parts of the country this time of year is no fun unless you use a Kevlar layered tire, thorn resistant tubes, and tire liners.