Well...first off, they're really fun to watch when they hunt. There's a wide variety of types, but my favorites are wolf spiders. They don't wait around in a web for their prey. They chase it down.
Also I love the grouping of their eyes. Two big ones on the side, and six smaller ones bundled in between in an organized stack. When light flashes on them, they glow, and since the wolf spider is a nocturnal predator, sometimes you can see their tiny eyes in the yard when a light is shined on them.
Plus 8 is my favorite number, and since Spiders are arachnids, they've got eight legs. (Not counting the pedipalps, which are modified chelicerae, aka mouthparts.)