Gust load as in a VG diagram is a vertical gust and not a horizontally veering wind gust in a surface wind.
You’re not increasing the G-loading on the airplane with a gusting crosswind.
In a light GA airplane I would go with the lesser flap setting as go around climb performance tends to be very anemic with full flap.
In large aircraft you would increase Vref with half the headwind component and the full gust.
Obviously with a maximum.
In that case you would usually go with the lower flap setting as you would get close to the max flap speed.
Both cases flap 25.