Most important quality is structure.
I use this and form interchangeably,I like to know there's a meter to follow,tone voice is inflecting,objective behind this piece(even writing for nothing could mean they wrote for fun,also stream of consciousness)
With structure comes something to follow.
Along with basics,since they're foundation and how true is one sticking to form(Haiku,Acrostics,Sonnets)
Finally,figurative language.
They're not a deal breaker,I probably started by just saying what I want to say and respecting poem in process.
However,figurative language helps,as this makes poems fun and difference maker in generic poetry and organic poetry.
Organic being original,generic being cliché.
What would you define as an important quality in poetry?
Truth. I want to feel like the poet means what thy are saying. You can spot a fame hungry IG poet a mile off.