Personally, I never really counted the RP2350 as a successor. It's a different animal completely. A 2040 successor would be something like 4x cortex-m0's or a faster clock with more ram or whatever, the 2350 has completed different capabilities and components and can live along side the 2040.

I feel like the preferred one is the 2040 simply because it's cheaper, and capable enough for the vast majority of use cases at this point.

Edit: yes I know RPI called their board using the 2350 the pico 2, but the 2040 chip itself is used in more places than just the pico and not every one used the 2350 as a v2.

Cheap. Also, a large part of the tinkering community never moves past soldering or perf board + lack of cheap 2354 boards. 2040 is already good enough for keebs and most projects. 2350 had eratta E9 published (gpio lockup) which killed its initial adoption rate for more advanced projects PicoLogicAnalyzer, protocol emulation, etc.