Which Street Fighter game offered the best gameplay in your opinion? (SF2-SSF4)

In terms of Depth, skill and overall fun factor, which Street Fighter game do you think gets the job done in all 3 of these factors the best? I have been quite curious to hear various opinions on this

(forgot to add ST at first T.T)

For the love of God, NO VERSUS THREADS.

+1 for EX series .

i dont know why youd lump CE/HF together but from a pure gameplay standpoint its obviously HF. i might enjoy different games more at any given point but it has the best balance, most refined system, most intense strategy, etc. etc…

Street Fighter Zero 2 Alpha, Street Fighter EX Plus Alpha and Street Fighter II Hyper Fighting are all equally as good as each other.