For my favourite Transformer toy released in 2015 I'm going to say Mp Tracks, he wasn't everyone's cup of tea, but for me he was my most anticipated official release, and he delivered just enough. Some may find the transformation complex for me it's just the right level of complexity and ingenuity I like, and a nice sparkly blue which helps me get over his being a bit hollow. Runners ups would be MP Magnus who I find a bit boring in robot mode, but wow that transformation and MP Blue Bluestreak who is the best looking Datsunbot IMHO.
My number one unofficial Transformer like toy this year is Maketoys Cupola who I wasn't anticipating and picked up mostly because I got it for a good price, and then proceeded to blow my mind with the level of quality and plain fun to be had. Again this guy hits the level of transformation complexity I like in a toy, IE, reasonably complex but rewarding so I can't help but pick him up and transform him, plus he looks really imposing.
And my favourite transforming toy of 2015, and overall favourite for 2015 is not a Transformer or homage to a Transformer but a Valkyrie Bandai's DX Chogokin VF-19 Advance which did for me pretty much all of what my previous picks did.
Oddly enough I don't actually agree that MP 1 is better, I find MP 10 to be as good a toy as MP 1 as I prefer his sculpt and size, not just because he scales with the new stuff but because I find MP 1 is just slightly to large and unwieldy. Still neither toy for me is an overall winner, what I meant on the other thread is simply that MP 10 isn't really any sort of major upgrade from MP 1. Though personally I think we are now in an era of sidegrades now as while sculpting has improved articulation has largely gone backwards, just look at all those Combiner Wars Autobot cars.