My favorite sinnoh pokemon are Weavile, Lucario, Torterra, Empoleon, Gallade, Yanmega, Togekiss, Gliscor, Porygon-Z, Staraptor, Bidoof ( its so pathetic looking and useless in battle i find it cute XD, Although i hate Bibarel), Munchlax and Drapion.
My favorite of all sinnoh pkmn is Weavile. It just looks awesome and its High Attack and Speed serves very well on my team.
My least favorites... basically the new evolutions. Electivire, Magmortar, Tangrowth, Probopass, Lickilicky and Magnezone. Rhyperior is just... urrrgh. Some new evos i liked ( mentioned above ). I really dont like Infernape, i just dont. Spiritomb is freaking stupid, as is Rotom.
My least favorite of all Sinnoh pkmn, Rhyperior, i cant stand the design and gamefreak ruined the Rhydon Family. coz Rhydon is one of my all time favs. I hate you gamefreak.