I’m going to give you my personal experience, If you want to hear it.
Read range in order
F.
D.
E.
C.
B.
A.
F. Almost Card read ranges, pretty similar to Fobs
D. Amazing read range for its size, and surprisingly robust, Mines in my forearm and I’ll frequently knock it, drop my back pack and catch it on it and it just keeps on ticking.
E. I have and have had a few of these and the read range is really reliable and the only time it may struggle is with a battery powered reader, Padlocks or similar, but in the same breath, some just work really well, hotel doors, chinese relay boards etc.
C. I have 3, they are still very usable, but in my opinion, not quite as good as E., I know why Amal has move away from the copper E.'s but I have had nothing but great experiences with mine which is all I can comment on.
B. & A. have negligible differences between them, But there has been a couple of tests that show an xEM tests ever so slightly better than a NExT
and likewise an xNT slightly better than the NExT
These are so close in performance, it’s barely worth seperating them.
They work well, when you know your implant and know your reader, getting a succesful read should be easily attained.
I don’t have unrealistic expectations of mine, I know they probably wont work with a Hotel lock or door lock, BUT they still could if you find the right one.
I have never had a problem reading mine with a phone, a proxmark3 or a flipper.