Search the sub for previous responses - question has been asked and answered many times. Enjoy your trip :) More on reddit.com

Full disclosure: I worked for two of three 'main' tour companies (and have friends in others) for about 15 years. If you want history: Mercat Tours (daytime). Their night tours are good too, but I found some of the guides to be a bit "Am-Dram". Of the three underground tours, their vaults are probably the most impressive. If you want "Ooo! Spooky!": Auld Reekie Tours. Cool underground tours. Genuine, working pagan temple inside. If you want awesome, scary comedy fun: The Witchery tours Longest running tour, I believe. It's a good fun blast, while walking around the old town. If you want first class, professional storytelling that's both funny and terrifying: City of the Dead tours. The graveyard tour is probably the best. They also do an underground tour, and a "double" tour that goes to both areas (vaults and Greyfriars graveyard). Each guide is slightly different (no fixed script) but they're all awesome. If you want usurpers who utilise unfair business practices, advertise "free" tours, and send their recruits on other tours to steal stories (and jokes), then tell them wrong: Try Sandemans. The guides are good folk, probably, but the company sucks ass. Some of the other free tours are actually pretty good. Also, special mention to the Edinburgh Pub Crawl. More on reddit.com

Well Mercat Tours is the first and the only 5 star tour company in Edinburgh, and they have exclusive access to the most extensive set of vaults of the South Bridge. The Ghost and Ghouls tour is only £14 per adult and is 2 hours of gory and real history and includes drinks in their underground Cellar. The Hidden and Haunted tour is the adult only 1hr tour which is £11 and includes paranormal happenings in the vaults. The newest tour they have is the Doomed, Dead and Buried tour, it goes to the underground and the Canongate Graveyard. Here is their official website. My source is my girlfriend Victoria who works for Mercat so again, slightly biased! I personally have been on a bunch of the tours and had a brilliant time and the guides are fantastic. Edit: TripAdvisor More on reddit.com

The Edinburgh Dungeon is like a haunted house ride at a theme park. There are actors, some ride elements (a boat and a drop ride used to feature). The staff guide a group of you through different sections that all focus on various nasty bits of history. Pretty fun, especially for older kids. I used to go every year or two when I was wee. Ghost Tours could mean a variety of things, but the most popular is probably Mary King's Close. This was a series of real underground vaults that people used to live in. It's a set tour where a guide will take you underground into these vaults and tour you around. There are no actors. It's an underground history walk. More on reddit.com