For me it's between ninetales and rayquaza. Not for stats purposes but mainly because they had a main influence on my childhood with pokemon. Firstly ninetales due to the fact that I always wanted a golden retriever as a kid (even though it's a fox pokemon lol). Ninetales for some reason resembled a golden retriever to me and well, as of now I just stick with ninetales allot since I think it's a pretty cool pokemon in my opinion. And damn is will-o-wisp a helpful move xD. Now for rayquaza as a kid I would think," Wow, that legendary looks so cool!" but currently I just like it's stats and design in general. Not to mention how cool it's new mega evolution is.