Nitro

Nitro, from The Last Knight toyline, is a real surprise. He feels like a toy from the 2007 or ROTF movie lines, and in a good way. Great robot mode, interesting and involved transformation, pretty good alt mode. The Titanmaster interactivity is just a cherry on top. While my TLK collection is pretty small (voyager Optimus, Leader Megatron), I can easily say that Nitro is my favorite.