My favorite CAP would definitely have to be Tomohawk. As a fairly mediocre player and teambuilder myself, I've always found myself going back to balanced and bulky offense teams for the balance of defensive and offensive characteristics (since I hardly specialize in either). As such, I've always been partial to Pokemon that can take a hit and dish them out as well, which is why I have been very fond of Pokemon like Landorus-T. Tomohawk essentially sums up all of my competitive preferences in a way almost nothing else does. Fighting and Flying are my two favorite offensive types to abuse, and I've always been fond of a potential Pokemon with those STABs, which Tomohawk is. It even has the moves to abuse it; very little likes taking the combination of Aura Sphere and Hurricane, especially when backed by a very nice base 115 SpA stat. Tomohawk is also no slacker in taking hits with its great 105 / 90 / 80 bulk, Roost, good resistances with a Ground immunity, and Intimidate. It can even utilize Prankster SubRoost and Toxic to a great effect for a defensive stall set. Tomohawk also fills several great support roles with moves like Rapid Spin, Baton Pass, and even Healing Wish. Tomohawk just has the potential to fill so many great roles, and it makes a great symbol of bulky offense to me.
Necturna is definitely my second favorite. I have to agree with Birkal here, I was a bit worried as to just how a Pokemon with a one-time Sketch would work in OU. Since we were giving Necturna access to any one move it wanted alongside its natural movepool, we were walking very thin ice as to just how good we could make it. After all, we wanted a Pokemon that could actually abuse Sketched moves, but we didn't want to make it so good that it would break the metagame with the appropriate move. As far as the concept goes, I think Necturna was a slam dunk. She's just good enough to abuse Sketch in a fantastic way with several viable sets, and yet we were able to balance her typing, stats, and natural movepool in such a way to prevent her from being broken. She definitely deserves a mention.
Also, I'm not a huge fan of Aurumoth. Maybe it's just the direction that the project went, but I just feel that we gave Aurumoth a combination of stats, abilities, and a bloated movepool that just made it too good to be true.