The Starship set is the "base" set that was available first in the UK. It features a little player elimination (but not as much as Love Letter does), and a little interaction with the Ruins (discard area). I see it as a kind of halfway-house between what Lost Legacy should be, and what people were expecting after playing Love Letter. It's a bit of a washout on it's own unfortunately, but some of the cards' abilities are sublime.
Flying Garden really ups the game play, setting itself apart from Love Letter completely. There's a lot more interaction with the Ruins, and the Investigation Phase at the end of the game starts to properly shine through. Keeping a track of people's hands becomes a very real (yet challenging) requirement. This combined with The Starship plays so much better than either individually.
I wish I could comment on more of the sets, but no others are available at my FLGS yet!