it depends on what you want to do!
you can load a Pi up with a lot of great wifi radios and likely get more data, but the effort and complexity increases, and so does your required (initial and ongoing) input of effort.
Swap-able power banks
Cost is whatever you want to spend
As many of powerful radios as you want
As much storage as you care to pay for
Kismet is the gold standard for network detection
The new web UI means you can even keep tabs on it from your smartphone while it sits in your backpack
Currently the Kismet export-to-wigle function doesn't upload cellular or bluetooth signals (only a PR away!).
more "moving parts" -> more things that may go wrong (harden your rig! invest in a good case!)
more manual effort to set up and maintain
You need to pick a good GPS (see https://www.youtube.com/watch?v=swCSBFO-w6M
if you want a 'fire and forget' setup, an Android device can get you a lot of points without a lot of effort, but you'll have less configuration, less reach
It Just Works (generally pretty reliable)
Used Android 8 handsets are cheap
Upload from anywhere, if you add a data plan
Scriptable launch/exit/shut-down/upload has a GUI in Tasker / other cool "intent" suites
We think we wrote an OK stumbling package
Most android phones support multi-constellation GNSS
Bluetooth and cell come standard
The radio in the handset you buy is all you have to work with
Ditto the GPS
In general a lot less control and less detail than Kismet!
Most handsets don't have swappable batteries (but power banks still work)
Probably overall fewer wifi points per run