I really like Imperial Settlers, but I’d tentatively recommend the 51st State Master Set over it, even though I like IS better. 51st State came first and it’s the same kind of gameplay but everyone’s playing from a common card pool. IS is kind of hard to get into because everyone’s deck is trying to do different things in different ways, and while I prefer that overall, it makes it quite a bit harder to learn.
Also I’ve got a handful of expansions for IS and I never play them because it’s too much faff to swap cards in and out of the different decks.
There’s a roll and write Imperial Settlers game now. I haven’t looked into it but that might be a good compromise too.