power consumption, ecosystem. The non-RISCV ESP's are a very wonky architecture, and while there is lots of ESP code out there, finding stuff that just works i

power consumption, ecosystem. The non-RISCV ESP's are a very wonky architecture, and while there is lots of ESP code out there, finding stuff that just works is harder than one may think. Meanwhile, pretty much all NRF52840 stuff you will run into just works, and works reliably. The toolchains and underlying pieces are also basically only supported by EspressIf (yes some work is upstream, but unlike ARM Cortex, you won't find a lot of help from others on Xtensa). Real debugging of NRF52840 stuff is also easier to do because of this - lots and lots of debug tools work. You will also get much better documentation out of Nordic. Now, this is mostly about Xtensa, and almost certainly one of the reasons that they are moving the ESP's toward RISC-V. I don't have enough experience with the newer RISC-V ones to give you a view there.