Black/White > Emerald >= Platinum (so far) > HG/SS > Diamond/Pearl > Crystal > FR/LG > Gold/Silver > Red/Blue > Ruby/Sapphire (from what I've seen and read) > Yellow.
Yellow so low because of how ridiculously unbalanced and easy-even-for-Pokemon it is, but I might kinda-sorta enjoy playing it more than Red/Blue and Ruby/Sapphire despite that just for how goofy it is. With HG/SS completely outclassing Gold/Silver, I might even enjoy messing around with it above them. So Yellow's ranking is really... controversial. >_>
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K | H | A | Q | Q | A | H | K
"we're about 50 years behind the rest of western society." -icon on B8