How about “all of them”. 
Technology and how it reproduces the sound is what interests me the most, and I definitely don’t imagine myself with a “wall” of headphones like Zeos, so I want just one of each.
There’s also “balanced” IEMs, and a few rare headphones with AMT tweeters in them.
Yes, I want this too. No, I’m not rich. I’ve started “the cheap AF headphones thread” and “the too good for the price list”. So, yeah. Even the cheapest stuff is really, really interesting (Like KZ AS-06 full-balanced 3-drivers for 30$), and sounds really interesting too (I already have KZ ZS10 Pros – will give to a friend if I prefer the AS06).