Raichu
Best how? From a battle perspective, Pikachu is far from the best, even from a popularity perspective, I wonder if Pikachu is the best simply because it's the only one non-Pokemon fans have ever heard of.
Pikachu's popularity isn't because it's the best, it's because Pikachu has the best marketing.
Pikachu is EA.
Fun fact, I buy my best friend a pikachu plushie every year for Christmas in addition to her gift, because she likes Pikachu and Nintendo has released so many unique variations that I could never possibility buy her all of them.
I mean there are at least 29 different pikachu plushies [http://www.pokemoncenter.com/s?defaultSearchTextValue=May+We+Help+You+Find+Something%3F&searchSize=60&searchKeywords=pikachu&Action=submit&field_subjectbin=&field_size_name=&field_generic_text_1-bin=&searchRank=generic-one-asc-rank&searchPage=1&searchBinNameList=subjectbin%2Csize_name%2Cgeneric_text_1-bin] for sale on Pokemoncenter.com right now and that's just the new ones.
Unfortunately they don't have a "dictator Pikachu" plushie.