3 Individuals you say?
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cracks knuckles1) Rook
Well, the best of the best has to be Rook. His vehicle mode has great molded detail and paint, rolls very well, his HFG integrates the best as does his other weapon. also virtually no robot kibble visible and his head, despite being visible, really isn't at all. Transformation is a blast. Robot mode has awesome blue, black, white and silver detailing an he has an awesome head with the Rook chess piece styled top and American football helmet face, plus his symbol on his head. He has the best articulation and even includes ankle tilts. His HFG also integrates all sorts of ways into robot mode and he can do the hulk hands, which is the best thing ever. And he is the best combiner arm as he is just beefy and buff.
2) First Aid
Another no brainer for me. I love the character as a whole but the figure nails it. The vehicle mode has lots of nice red and silver paint overtop the white and the HFG once again stores nicely, as does his axe. He has a tough look to him that lets you know he can get where he needs to go. Transformation is fun and he make the best leg. Nice kneecap, not terribly wide or skinny, and he fills out the whole leg evenly. As an arm he makes for a very hefty and buff piece of work and makes Defensor look like a boxer. Robot mode has nice paint and mold detail and his head sculpt is beautifully IDW.
3) Air Raid
My favorite aerialbot and the best of the fly boys in my opinion. His jet mode looks very sleek and he integrates his robot mode undercarriage better than the rest. His wings are fully posable so you can pull off all kinds of jet attack modes and looks. The wings ability to move a lot helps with arm and leg modes, as he matches the width of the HFG perfectly in both and looks dead sexy. robot mode is a joy too with great detailing, paint, and adjustable wings. He is the ultimate aerialbot.
Now, if we were to include the legends and leaders that are not technically supposed to combine, Ultra Magnus would be #3, but I won't bore anyone with why unless they request it. and torso-bot wise, I give the win to Cyclonus (another one very high up on the list)