1. Hasbro DOTM Ultimate Optimus Prime - as mentioned on the packaging, YES, it's the biggest Prime ever...with the wings expanded, it stands at over 22 inches...
2. Takara DOTM Jetwing Optimus Prime - this would definitely compliment the combined ROTF Buster Prime + Jetfire...
3. Hasbro Classic Optimus Prime - very rare nowadays, especially since the FP's trailer was launched...
