What I consider to be A list titles are machines that have a highly regarded reputation, instantly recognisable and price tag to go with it - I must stress that this does not mean that they necessarily deserve being in that A list group of machines.  Just because someone paid $5k for a machine doesn't mean that it may be the best all round machine.  Whether it is the dealers or collectors that create the hype around a particular machine or whether it is genuinely a great machine is up for debate.  Things change, for example, if the new Judge Dredd movie is a success, I would expect the value of that machine to increase slightly purely due to the hype at the time.

This is just the way I look at it.  To group machines in order of game play, art work and the like is near impossible as everyone has different tastes.  There are however some all time classic machines, from all eras, that demand their place in the 'A' list.  Whether we all agree on that particular title or not will always remain an issue but for something like that, I would have to say majority rules.