Trust me, there is nothing bad about the KZ EDR1, EDR2, or HDS3. I wouldn't own multiple pairs nor recommend them if they were junk.
Plus I recently just picked up yet another spare set of EDR1 and EDR2, because they were under $4 ($3.77 shipped for the non-microphone version) - 1/3 of the price of the Einsear T2. How's that for an attractive price tag LOL?
The Einsear T2 is great too, but isn't 3xs "better" than the EDR1/EDR2 in my opinion.
I don't have any experience with the Piston 4, but I do have the Xiaomi Pro HD and also the Xiaomi Piston "Fresh Version". They are both great IEMs for the money, and the Piston "Fresh Version" is a tremendous deal for $3.99 (on sale at Gearbest with a coupon quite often). There's a piece of foam stuffed into the nozzle of the Piston "Fresh Version" though - for best sound you'll want to remove the foam using a sewing needle (a 30 second procedure). Xiaomi Pro HD can be a tad sibilant on some tracks, and some find it lacking in sub-bass (which throws off the overall balance). To improve the sub-bass, you will need to seal the front vent with a small piece of tape.
Where are you located, and were you planning on buying from Aliexpress? You should be able to get all of those IEMs from Aliexpress (including the Urbanfun Hifi hybrid, one of the best on the list).
Also, be aware that there's 2 versions of the MEMT X5 - an original version and a new version (with different tuning). I should also mention that there's 2 versions of the Urbanfun too - one is the hybrid with a grey cable, and the other is a single driver beryllium with a black cable. You'd want the hybrid with grey cable, which confuses a lot of people.