I love neutral expressions because it makes it easier for me to imagine different expressions on their faces when I'm playing with them. I find it harder to say, imagine the character expressing an emotion that's opposed to what's sculpted on their face. e.g. BW Ultra, TM & TM2 Megatron all have snarling "poo eating grin" faces (as do BW Galvatron and Magmatron). This makes it look weird when I'm imagining the character say laughing ("bwahaha!"), having an evil smile ("Yesss"), being stoic etc. The other day I was playing with Animated Ironhide who was in charge of guarding an extra-dimensional prisoner... there was a prison break and Ironhide was overwhelmed. Yet the toy has this smirk on his face, which looks weird when I'm trying to imagine him being terrified. So I prefer a neutral expression as I find it more 'versatile' during play. Pre-fixed expressions work well on busts and statues, but I don't like them so much on action figures. They're toys, not poseable/transformable statues (IMHO).