My collection of universal IEMs, by personal ranking --
Sony MDR EX-1000 (discontinued)
Sony MDR EX-600 (discontinued)
Shure SE-535 (2sets, both bronze & clear)
The Sony MDRs have the clearest, deepest, most powerful bass, followed by the XBA-4s. If you like EDM (electronic dance music) like Deadmau5 or Kaskade, you can't find better IEMs.
There's subjectively little difference in my kind of music wearing the Shures or Westones. All seem to fuzz up at the BA crossovers. The music is definitely "murky" compared to the Sonys. Not in a bad way -- they make the music sound like a hi-def radio channel. But after you've listened with Sonys it's hard to transition back.
The Westones have the thinnest cable, Shures the thickest cable. Shures are very comfortable to wear. In contrast, Westones with Comply tips can make you forget you're wearing them.
IE8s are tweakable -- there's an adjustable bass setting.
Of these sets, the XBA-4s and IE8s do not have field-replaceable cables. This should be a priority to safeguard your investment.
I regularly rotate between all these sets, and find that I'm constantly fussing with eartip size and shape. Olives with one set sound best; triple flanges elsewhere are the key. Unfortunately, I can't make Complys work everywhere. :) (Part of the problem is that each IEM model speaker aperture is different in diameter and length, the housing weighs differently, and the mass is balanced differently between dynamic and 3- or 4-BA speaker types. Even wearing all cords over-the-ear, the cord weight and stiffness influences how the IEMs sit. And if you wear while exercising or in other sweat-inducing environments, you have a whole extra set of conditions to consider.)
If the SE535 limited edition (reds) were obtainable at the prices I paid for my two regular sets, I'd consider adding to my collection. I wouldn't pay a nickel more, though. The red housing is like slapping a Lexus sticker on a Camry. :)