Most people would say Austin Powers first film was the best and by and large, Goldmember was the worst (and rightly so, it's garbage).
Out of four:
AUSTIN POWERS: INTERNATIONAL MAN OF MYSTERY ****
AUSTIN POWERS in THE SPY WHO SHAGGED ME ***
AUSTIN POWERS in GOLDMEMBER **
The law of diminishing returns doesn't bode well for the upcoming fourth installment...
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"Yes, citizen, there is no cause for alarm -- you may return to your harpsichord."
"Yes, citizen, there is no cause for alarm -- you may return to your harpsichord."