Brett - Don't restrict yourself to Williams games. I know the Harlem Globetrotters on eBay was sold out of WA, but that buries Phoenix, Gorgar and Flash IMHO. Only Firepower would be considered slightly ahead of HG.
I'm a bit "one eyed", but you need to broaden the net a bit ?
A bit one eyed - and you say FP slightly ahead of HG?
You, sir, are being highly controversial!! 
Absolutely ! This is EXACTLY what is so good about Collecting Pinballs. There is such a diversity of machines and there are games that were part of our formative years. I recall WALLS of Ballys during the route days. By 1981, The Systems 4/6 and GTB SYS1 were parted out or THROWN out. They were simply unreliable. As a kid, the service calls were usually WMs or SYS1. Even the EMs were more reliable. The locations the machines were operated in were always close to the workshop for one reason - they continually needed to be serviced. Even on these locations, the WMS machines were nearest the door - so they could easily be carted out for repair. When I search through boxes of old parts I find really interesting stuff. Mainly NOS GTB EM or NOS Bally SS. Why ? Because they RARELY broke down. These parts were not needed. But I find boxes of old Williams games - boards, displays, mechanisms. coils - even backglasses. Why ? Because they were so unreliable - they were parted out.
When I speak with my father about the SS Days - he remembers how good the Bally and Sterns were, and when I speak about the System4/6 games he stops me and says -"I feeli like I'm going to throw up". This was common amongst operators of the time.
That's my obvious bias explained (from a historical point of view)
Pound for pound (like Ford VS Holden), the Ballys were simply a class above their competitors.
Apples for Apples (1980) - Compare a Firepower with Fathom. No contest !
Seriously - if I had a firepower and you had a Harlem Globetrotters - I'd swap. I'm quite happy to be criticised over my opinion - but that's a machine I used to play on location and it was part of my pinball childhood !
ok, I didnt even think of a title other than Williams because everyone always says bally/Williams etc etc.
Question - what is THE BEST title I shld buy being a game made prior to 1981, being a SS machine or even earlier ?
(if u could have ONLY ONE MACHINE prior to 1981, what machine must it be ? 
I really want the best of the best for this era. Is it Paragon, Is it a KISS, is it a Atari Hulk or Superman ? which one must I add to represent everything earlier than 1981 ?
I will then buy what u guys vote the best title is. Majority vote wins 
Won't be KISS. Leave that for the KISS fans with deep pockets. It is not a "player's" game and only showcases the INCREDIBLE art rather than the gameplay
GTB Hulk - Great game, but hard to track down. If you want a Gottlieb from this era it would be a Joker Poker or Genie
Atari Superman - more of a collector's game.
Williams - Flash or Firepower. No use buying a Black Knight as you have a BK2000.
Stern - Meteor, Galaxy or Flight 2000
GTB - Genie or Joker Poker
Bally - Paragon, Fathom, Viking, Medusa or Flash Gordon
If you simply want the best SS it would be Paragon, Fathom or Meteor.
