Of the "modern" poets beside Buk, I found Seamus Heaney and Joseph Brodsky to have the most to say. Of course, one could add Ann Menebroker, Diane Wakoski, and a few others into that category.
I would also add Nazim Hikmet into the category of important words, but he's probably of an earlier genre, and the translations are hard to ignore in terms of what the original words are worth.