most accurate iem?

[suyan]

What's the most accurate iem? I'd like to see measurements to support as well if possible.

I previously owned the er-4S, which measures pretty flat beyond a treble spike. I ultimately found them sibilant and bass light (in terms of bass-feel) and "upgraded" to the ck100, which has quite forward mids, and accurate treble and bass from my perception (but I haven't seen a ck100 fr a graph). The bass has noticeably more feel than the er-4S, and the er-4S is flat so I'm guessing bass is less accurate here? The ck100 has a soundstage about 1.5 times the size of the er-4S and does imaging quite well.

For my next purchase, I'm considering the ck10 which is supposedly pretty accurate (more accurate than the ck100 regardless), but with a smaller soundstage. Of course, this next purchase is in the very long term (I'm poor).

In any case, I'd like to hear your thoughts and any evidence you bring to the table.