This is by far my favorite hiking app available; it's free, easy to use, and can be accessed from basically anywhere in the world. All Trails pinpoints your location and gives you the top 25-or so hikes around you based on requirements you set including length of hike, difficulty, views available, and the type of terrain. You can also track each hike to see your elevation gain, average speed, and total steps taken. You can also views other users' recorded hikes and link to their maps to ensure you're at the correct starting point and stay on the right track.
My favorite part about this app though, is it's capability to link to Google Maps directly, so instead of having to type in some weird trailhead name and google freaking out on you, it drops exact coordinates to help you arrive at the correct destination! Lots of users also leave helpful hints after they've done the hike, most of which are extremely helpful to read before going on the adventure yourself!