Thanks for your advice, it seems that the solid advice is just try on the masks and choice the one that feels the best for me, then decide from there. So I'm gonna do just that, thanks for helping me out.Hi... Your mask is without doubt the most important part of your kit... If it's not comfortable or fogs up then you can't see who you're shooting at or who's shooting at you...!
A lot depends on you... Like others have said try on as many pairs as you can before you buy... Everyone has different heads or wear glasses etc etc... so different strokes for different folks...
Personally I like i4's... Good wide range of vision and for me are light and let in plenty of air...