I use Panasonic CF25 Tough book cheap as chips, indestructible but a bit slow and temperamental, no USB, have to use serial port for GPS
CF 71 works well but not as tough, I did drop one down some concrete steps when on and when I put the keyboard hard drive back in it still booted up and ran OK (still working today!) I can highly recommend the CF71 as its cheap and works well with Memory map and has USB 13 in screen
Now the CF18 is a master piece, light, works very well! And does loads of other things to! Totally over the top and very desirable if left in the Landrover!
The Batteries are expensive to replace on all these though but happily run on external DC power with converter (I have run CF25 and CF71 DIRECTLEY wired to 12 power supply and they don’t run flat
So my opinion for what its worth is CF71, works OK for mapping and no disaster if stolen! (£60?)
Gordon