I tend to listen out and go for one that it seems few people are at. I used to go for an xx50 alt, but don't think it is worth it, when just over 1mb different (and within altimeter tolerance anyway) will swipe it all.
Main worry that crosses through my mind is people calling an altitude, but no knowledge if they are on the regional, or whose QNH (or QFE!) thy are using. Nothing like a Mk1 eyeball looking *outside* the cockpit