Spoiler, there's no winners or losers here really, it all depends on your usage.
I have had the smaller 600ml Petrel G3 pot for a while and it is perfect for one person out camping. The Petrel G2 750ml pot is ideal for one or two campers and to be fair if I had to make the choice of only buying one then the obvious winner for me would be the larger 750ml Petrel G2 as it covers all the bases for me.
For the low price of these pots I think you would struggle to find a better bit of kit.