Realistically, for me, any gun that actually looks what I'd call 'sorted'. Don't care on the platform or the make, but it's really bloody rare I see a gun with a setup that makes me think "that's actually well done" (obviously excluding the comedy guns in this one). I get people might be limited on the batteries the have in relation to the gun and their budget etc, but if you can't afford to setup your rifle in such a way that all the weight of that Large type NiMh isn't entirely dangling directly from the wire connection.. well I think you should just wait til next payday before attending another game. If anything for your own sake as that's just not a good thing for the battery, the gun or the shooter.
Also anyone that actually uses their attached foregrip, be it vertical or angled. I almost never see those used, they're just hanging out in front there while the shooter grips the magwell all day long. Not saying people 'aren't allowed' to grip the magwell that's entirely personal preference, but it's rare I see anyone actually utilise the foregrip they've paid for and attached, so that stands out to me.