Thanks Ian, interesting topic. I think making comparison is tricky because one either seeks to equate the benefits received or the ease of earning status – though as the latter can vary widely within alliances, probably best to stick to the former.
Personally, I would characterise it slightly diffierently – each alliance has a lower level tier that does not include lounge access. Star and Skyteam each have one premium tier (Gold and Elite Plus respectively), which includes all benefits, including lounge access – while oneworld has two such tiers (Sapphire and Emerald) with some benefits held back for the latter. So, I would compare these four tiers against each other.
Oneworld’s subdivision of its premium tier passengers can work both ways. If flying extensively, oneworld’s Emerald tier grants more exclusivity and provides access to some swish First Class lounges and Fast Track at selected airports. To be fair, how much difference there is between the lounges available to Emerald and Sapphire tier members varies substantially from carrier to carrier.
Skyteam has fewer carriers with First Class but when there is a First Class lounge, that’s sometimes available for its Elite Plus members. Similarly, its SkyPriority is much more widespread and consistently available to all Elite Plus members. I have less experience of Star Alliance, though I know that in some cases, the First Class lounge is only available to the airline’s own top elites.
But I agree with your basic conclusions – oneworld offers more of an incentive to frequent Business Class passengers that they would get access to a lounge they would otherwise not get. I do find SkyTeam has done most to provide a consistent offering – including SkyPriority and the Guaranteed Reservations on long haul flights.
Tom, as for the domestic access to lounges, I think oneworld and Star Alliance win hands down over Skyteam. Each alliance had to decide what to do about those airlines who, in their domestic markets, offered a paid-for lounge service (primarily the USA and Australia). Oneworld and Star Alliance decided to include domestic flights in the lounge access policy, but exclude UA, US, AA and QF status members flying domestically on their home carrier (but not status passengers of alliance partners flying on the same flights). Skyteam’s approach was to exclude all domestic-only itineraries from lounge access.