It depends on the poem, and on the reader. Some poems work really well for reading aloud, at least by someone who knows what he’s doing. There’s a real pleasure in hearing a good poem recited/performed/read really well. I’ve never gotten tired of hearing my Dad do “The Cremation of Sam McGee,” for instance.
But some poems actually work better on the page; and a bad reading of even a good poem is excruciating. (And as Skald said, not all poets are good performers.) So as a general rule, which certainly admits of exceptions, I’d prefer to read a poem for myself.
And that means, read silently, but slowly and carefully so that I hear the words in my head, getting the sounds as well as the sense. I could read it out loud, but the voice in my head is more versatile than the voice that comes out of my mouth.
A memory:
I’m sitting in sophomore high school English (American Lit.) class, reading ahead in the textbook, and I encounter, for the first time, Edgar Allan Poe’s poem “The Bells.” I read it silently to myself, and am blown away. I can hear the bells in my head as I read, and all the effects that Edgar was trying for work. I suspect it might be fun to recite aloud, but I am seriously doubtful that I could do it justice.
Then, at the teacher’s direction, the class reads the poem aloud. I forget how we did this—I think we read it in unison, but we might have gone around the room and each taken a few lines or a stanza or something. And the class’s reading, to my ears, fell flat. It didn’t even begin to do the poem justice.
What I’ve been annoyed by, in poetry readings/recordings I’ve heard, is the opposite: people (sometimes trained actors) who read a poem as if it were a paragraph of prose, so that the rhyme and the meter and the layout and the music of the poem get lost.
“Take care of the sounds and the sense will take care of itself.” -Lewis Carroll