I have not heard the E40, but I do have the E70 and CKR100. Both are very good, but quite different.
The E70 is fairly neutral, with a bit of emphasis in the bass. It can get a little sibilant depending on the track and eartips, but I don't find it to be overly so. The CKR100 has slightly less, but more impactful bass and a little emphasis on the upper mids. It doesn't pick up sibilance as much as the E70. The E70 gives me more detail and air and the CKR100 a smoother, slightly thicker sound.
I do find the E70 significantly easier to use. The CKR100 is noticeably heavier and it can be difficult to get a good seal while avoiding driver flex. With some tips, I get flex in one ear whenever I move my jaw and that's very annoying. It took quite a bit of trial and error to find tips that work for me. The E70, on the other hand has never given any trouble on those lines. I have switched tips to find the best sound, but have never had a problem with fit. I don't like the stock cable on the E70 very much as it tends to retain its shape after being coiled for storage, which can make it press into your face or stick out into space. It can be tricky to find reasonably priced replacement cables with the A2DC connectors, but there are some on Aliexpress.
If I had to pick just one it would probably be the E70, but it does depend on what sort of sound you like.