Normally I would say dub or nothing because I simply can't read that fast without missing what's onscreen. But for this show only, I'm going to say subs, if for nothing else then because closed captioning includes Boomhauer's lines.

Also, from everything I gather, fluent English doesn't come off to me as being a common thing in Japan. I'd love to be incorrect, but I've heard repeatedly that they mostly fall off again after high school and that their educational system looks down on errors so much they basically won't even risk asking questions, so they shrink from practicing verbally in front of actual speakers.

So the guy in the photo is a freeaboo