Weapon sets, especially for classicsverse. At least some C-clip compatible please, with a mix of character-modeled (i.e. Mirage's shoulder missile launcher) and generic. I don't mind them recycling old mold weapons either - things like Generations Blurr's sniper rifle set is worth a rerelease IMO.
I'd also love to see some improved head-and-weapon sets for specific characters a la Headrobots Bludgeon. Even if they just released an occasional upgrade kit to let us turn the endless Bumblebees into Bumper and Hubcap that'd probably get me buying another Bumblebee or two.