unless you happen to have a weirdly tiny head (in which case pictures are demanded) v-force grills ftw, lips do a great deal on these and the customer service from both lips and DXS is awesome.
grillz work, lens comes out quickly,doesnt fog up, foam is replaceable when it becomes sodden and disgusting saving you having to buy a new mask.
my tuppence
You may as well ask 'should I buy blue string or red string?'
Both systems are light, have a good field of vision and both have good quality lenses and (imho) great styling.
The fit/coverage is going to come down to your personal preference, I tried I4's at the cup for a couple of points and went back to my Grillz, but that's me.
Give your local shop a bell, try both on and see which you prefer.