Carboy neck handles. I bought one and never used it and probably never will. I don't trust the neck on a full carboy and an empty carboy is easy enough to move. For full carboys I always use a Brew Hauler... definitely a great piece of equipment!
I'd probably also suggest anything to solve a "problem" you didn't know you have... water treatment, Ph, etc. You may eventually want to play/experiment with all parameters but sometimes, if it ain't broke, don't fix it works fine. It's easy early on to worry about everything and buy too much.
Maybe a bottle brush... if it's dirty enough that you need to scrub, it's dirty enough for the trash. Rinse and dry immediately and you shouldn't have to be scrubbing!
I happen to like S type airlocks... I'll use a blow off tube if I'm expecting krausen to get to them -if they do get gunk in them a bleach water solution takes care of it. I just blow through with my mouth to clear out the gunk once the bleach breaks it down.