UAL is the one to beat. They are the best because of the Star Alliance
as far as I know, LH miles&more (also a StarAlliance member) offers many perks that UA MileagePlus doesn't, like:
* upgrades on any discounted fare
* class- and status-bonus count as status miles
* status-bonus on all StarAlliance flights
* RCC access when flying UA in the US
* status validity of 2 years
* and ... not being in chapter 11 ...
[This message has been edited by Rudi (edited Feb 19, 2004).]