I think it comes down to a few things...
1. How long does he intend to keep the PJ?
2. How often will he use the PJ?
3. How well will the room as typically used preserve the PJs native contrast?
4. Does he want to deal with bulbs dimming, needing replacement and often recalibration for a top quality image (or that even matters to him)?
5. How much of a hard core gamer is he?
If the room has 100% light control with dark walls/floor/ceiling, he values gaming and doesn't mind replacing bulbs and recalibrating the PJ, the JVC is the easy winner.
If there is ambient light, bright walls, he doesn't want to deal with recalibration, he plans to keep it for a long time and gaming lag isn't a big deal, then the BENQ is the easy winner.
Of course most of life falls in the middle somewhere so it just depends on his preferences.
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