They were a better enemy when we didn't know much about them, when they were just an army of drones looking to assimilate races and technology. They lost much of what made them an interesting and engaging species when VOY brought in Seven and had them defeating the Collective several times a year.
Commander Austin Harris, First Officer, Deep Space Nine (by FltCpt. Bossco)
8.01 - Darkest Before Dawn
(Chapter 8 added, 12/09/2015)