I was wondering if one multitool brand (or knife for that matter) is more rust-resistant than another.......
Rust is a nasty, nasty thing indeed. Even though all of the mainstream multitools today are made from "stainless" steel, every one of them are vulnerable to corrosion. However, you might not ever see a speck of rust, depending upon where you live and how you use your tool. Humid areas, near salty ocean waters are the worst.
Regarding the rust-resistance of various multitools, keep in mind that a polished finish will offer less of a foothold for rust to get started than a matte "bead blasted" finish. In general, the higher lustre the polish is, the better its ability to fend off corrosion will be.
~Bob