GMG is easier to use, and produces a more subtle smoked flavour.
Charcoal smoking in the wsm can give a more acrid smoke flavour if too much wood is used.
If you have the kettle there is an advantage that the wsm uses the same heat source. But the GMG is quicker to get up to speed and has the electronic temp control, food probe and the food cooking profiles.
To buy a PID for the WSM costs a few extra quid which puts the price to a similar region as a GMG
I like both
GMG is easier to use, and produces a more subtle smoked flavour.
Charcoal smoking in the wsm can give a more acrid smoke flavour if too much wood is used.
If you have the kettle there is an advantage that the wsm uses the same heat source. But the GMG is quicker to get up to speed and has the electronic temp control, food probe and the food cooking profiles.
To buy a PID for the WSM costs a few extra quid which puts the price to a similar region as a GMG