I didn't see the US version of LOM, I heard it was quite bad though.
A2A was not a perfect show but the last season and particularly the ending were very good.
The final episode answered to all questions regarding Sam and Alex and the twist about Gene was really interresting.
The door of the bar being the door to heaven was a nice touch and Nelson being somekind of St Peter corresponded to the character.
Besides I'm glad the writers choose not to have a happy ending.