If you find yourself not getting on with the screwfix ones GeordieNige I use the fake Oakley Jawbreakers which can be found on ebay for around £15 with free postage from China.
The glasses are nice and large so stop my eyes from streaming, but the vents in the glasses allow enough air through to demist them when riding, the still will mist a little when you are stopped but clear when you ride off.
My first pair have last week over a year now, I actually ordered a pair for my road bike and a spare pair, I did have an issue with one of the extra pairs being broken when it arrived, but the seller replaced free of charge!