The best for what? For whom?
I’ll assume, given where these sit in the overall spectrum of headphone prices and capabilities, that we’re looking at “a first pair of audiophile cans” for someone who’s not (necessarily) committed to the idea of collecting more.
With these parameters, I’d say 58X. They are a great step out of the world of lesser headphones, because they sound good with every type of music, their performance scales well with better equipment, they’re not too hard to drive, and a lot of people own Sennheisers so they’re an excellent reference point from which to learn about other headphones—if you aren’t averse to staring down the rabbit hole. :-)
There is a huge aftermarket for replacement pads, cables, etc., for the 600-ish series of Sennheiser cans. You can disassemble them without tools and replace just about every individual piece. If $150 sounds like as much as you want to invest in headphones, and you aren’t yet thinking you need to own more than one pair, then the ability to keep the 58x running nigh on forever, as well as the ease of adapting to portable, desktop or living room use with a variety of cable lengths and styles is probably appealing.
Later, when you’ve discovered that high end headphones, uh, procreate, the 58x make an excellent travel or loaner pair. Mine are with a friend who recently wound up in the hospital for a week.