I was never a big fan of Zapdos' original design, so I'm really liking this long-legged ratite version. It's like some kind of lightning ostrich. Don't dislike the other two, but still probably prefer the original Articuno and Moltres designs.
I think I may like that Electric Regi more than any of the existing ones.
Not too keen on the design of Calyrex, it's too abstract/bizarre. Though good on them for giving it Unnerve, it's a appropriate ability. Kubfu is meh, but the Water/Fighting form of Urshifu is pretty good looking. Not sure about any of them being Legendary pokemon (especially since you get given Kubfu as some kind of starter gift), but maybe they are sub-legendaries like Heatran, Latios, etc. (i.e. just rare, powerful pokemon).
As for old pokemon I hope return, I'd like it if all the starters got in, or at least Serperior (please give it a few good Special Attacks besides Leaf Storm and Dragon Pulse). Gliscor and Zebstrika would be other pokemon I hope return. But if I'm not to simply list favorites, then I hope to see as fair a distribution of types and generations as they can manage (admittedly harder to do if they include all the starters).
Of those confirmed to return, I like Garchomp but fear just what it will accomplish if they let it learn Dragon Dance. Nice to see Volcarona as well.