Are you referring to the new Sennheiser 58X Jubilee, the Massdrop collaboration? If so, that’s an objectively better deal than the 558’s, which were discontinued about two years ago.
If it’s between the old 580 and the 558…that’s an easier question. I’d go with neither. :)
I’d pick the 559, if you can find it, or step up your budget to the 58X if you think you can deal with the dual-entry cable and you want to see what Sennheiser’s premium lineup is all about. Oh, and if you don’t mind the wait time from Massdrop for the current shipment. I don’t know what the wait is right now because I don’t have a Massdrop account.
If you can find remaining stock of the 558, it might be rock- bottom cheap so if price is a big deal then that’d probably be the cheapest option. But again, it’s no longer manufactured.
Old 580’s are most likely to be used and in some state of disrepair, as they haven’t been made in years, and you might have a hard time getting any support out of Sennheiser.
The 58X is from the same higher-end lineup as the HD600/650, and has a sound that 99 percent of users will probably enjoy at least a little more than the 558. The only real advantage the 558/559 has is the single entry cable.
Hope that helps you out!