I'm guessing SB uses GFS (
www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs) as its underlying model from the USA.
BoM used to usually use the Australian ACCESS model (
www.bom.gov.au/nwp/doc/access/NWPData.shtml) in the first 24-72 hours and then ECMWF (
www.ecmwf.int/en/forecasts) in the longer term. However they have changed recently to use an ensemble of NWP models for the longer term forecasts. BoM also has forecaster input to manipulate areas where they know model data falls over but don't expect too much attention in the longer term.
I'm not sure about Willy Weather but from what I could see from their site they use BoM data.
windy.com will give you a choice between GFS, ECMWF and MeteoBlue (ensemble of other models) with alot of other stuff to look at as well as meteograms for well known kite/windsurf spots. ECMWF is the model of choice in my opinion for Australia but it always pays to have a look for consistency across other model data.
Whatever model you choose... its always going to be tricky with an extensive surface trough lying near the coast which is what it looks like at the Sunshine coast.