All the games on your list are good ones, IMHO. You really can't go wrong with any of these games in decent condition. Gorgar is probably the least desirable, but should also be the least expensive for comparable condition.
You have probably figured this out, but BH, HH, MGOW, and Volcano are all Gottlieb System 80 games, while Sorcerer, GL and Gorgar are Williams System 6-11 games. System 80 is not necessarily bad, but can be more tricky to work on. The Williams games might be easier to work on and troubleshoot when they go wrong.
And don't think a game will not have issues. They all do, sooner or later.
Having said that, my Black Hole has been rock solid since I bought it a few years ago, and I love it.