Video: There are actually five different Hill Valleys in the Back to the Future series. The 1985 film gets two versions (the one where they start off and the alternate Biff-ruled version), there's the throwback 1995 one, the awesomely futuristic 2015 version and the old Western 1885. Which one is your favourite? Trick question, it'd better be 2015.
Joel Bocko made this really fun video for Fandor Keyframe that compares all the different Hill Valleys and links together similar scenes so you can see how settings and situations that happened decades apart (the clock tower, the town square, Marty fighting various Biffs and so on) call back to each other across the movies. It's a great way to watch Back to the Future -- but really, any way is fun.