head-fi.org indicates that Audio-Technica's ATH-M50, while excellent, are probably not quite as good sound-quality-wise as Ultrasone's HFI-580, which are also twenty bucks or so cheaper.
This is probably true, at the time I was recommending ATH-M50s to everyone I don't think the HFI-580s were so cheap.
I have often benefited from recommendations for Things I Didn't Know I Wanted.
Given that Less Wrong is a community of unusually intelligent, critical, and self-improvement-focused people, I suspect we can generate a pretty helpful thread of product recommendations — perhaps even a monthly thread of product recommendations.
Rules: