You also might want to consider a non Wiliams game. I know many think that Bally / Williams pins are the only way to go so a TFTC or aStargate can be had cheaply and both are very good games. Getting to crypt jam isn't an easy task and decoding the seventh symbol although easier then crypt jam is a lot of fun. Stargate has been on Sci Fi for 7-8 year so everyone recognises it and multiball is pretty easy to get so the game appeals to the casual player. The game is deep enough however to keep a good player occupied as well. It is also the only pin I owned for years and never had to work on. 0 maintainance isn't a claim I can make with any of my Williams games.
Underrated = not very popular and now inexpensive due to ordinary aspect of it (looks, theme, sound) but with great gameplay...
70's = Silverball Mania (love it!), Gottlieb had a few good titles that are cheap, some others I am forgetting...
Early 80's= Flash Gordon (fast and furious), Paragon (cheesy sound, but is fun), most Sterns (Big Game, Lightning, Flight 2000, Meteor... all you can get at a reasonable price, and are quite fun...) , a few I am forgetting...
Late 80's= Strange Science (love that pin...), Genesis (I know...I know... but I like it, the midget is cool!), Heavy Metal Meltdown (love the guitar sounds and the gameplay). I personally think that this was a shitty era for pinball...
90's= BSDracula (hard as hell to master...) TFTC (fun as hell... it is the pin everybody goes to play at my place...), Demolition Man (a favorite)
Late 80's= Strange Science (love that pin...), Genesis (I know...I know... but I like it, the midget is cool!), Heavy Metal Meltdown (love the guitar sounds and the gameplay). I personally think that this was a shitty era for pinball...
I think the late 80's had some great games. Well maybe they were Williams games? like Pinbot, Taxi, Cyclone, Swords of Fury, Earthshaker etc...
Honeslty, I've played BR extensively at Pinball Expo '93 and I couldn't see why it was so 'hated'...
I would go for a Black Rose...if the price is right!
As for the rest of Marty's list, I agree...except for Congo, as I've never played it.
My $0.02
Frosken
Current 'working' lineup: ( 2 ) Flipper Football, The Shadow
Gone but not forgotten: ( 22 ) City Slicker, Dirty Harry, CFTBL, Big Shot, Big Guns, Black Rose, Judge Dredd, Indianapolis 500, Big Game, BS: Dracula x 2, Beat the Clock, Fire!, F-14 Tomcat, Getaway, Breakshot, Cheetah, Meteor, El Dorado, Nitro Ground Shaker, Chexx Hockey, Slugfest