Definitely two schools of thought... asking this question is as good as asking which is better: curry or laska? Some people think that single pane is good, others affirm that thermal lense works wonder. So which is which? If you are thinking about buying a mask, this question should be one of your considerations but not your ONLY consideration. I have used both single and thermal before, so if you ask me, I say both are as good as the other.
The brand V Force has always stick to their single pane anti fog lense, what it means is as simple as a single lense with anti fog coating on the inside. Afterall, if big teams such as Vicious, Icons and Aftermath are all using single lense goggle, who's that kid bragging that thermal lense is a better choice? Ok, so if single lense is good enough, then what's the point of buying a thermal lense mask? Simple, for its anti fogging capability. A pocket of air is contained between a glued goggle lense and a plastic sheet thus creating a "contained space" to prevent the mask from fogging. But the downside to this...is if the mask is not properly maintained. Wipe off the paintball marks instead of washing them under a running tap. If you need to give it a more thorough wash, clean it with a "watered tissue" instead. But yeah, anti fogging for thermal lense does work 1) if the mask is properly washed, 2) if the glue doesnt get worn out.
So which is better...? It all depends on the user.