좋아요 = (That's) good; (something is) good - plain statement with no special nuance.
좋네 = That/It is good! - said as if the speaker is pleasantly surprised.
좋게 = this has a couple of subtle uses which are too hard to explain without the surrounding context.
좋지 = It is good, (I am sure) - usually said as if reaffirming the fact to oneself.
좋소 = 1) "Okay" - accepts something (usually reluctantly), 2) It's good / We support it! - verbal support for some agenda.