Which Motown female performer of the 1960s had the most formidable vocal instrument? In terms of power, range and versatility?

I suppose most would consider it a showdown between Gladys Knight and Mary Wells. But I am not as familiar with the breadth of talent at the label in the 60s. Was Flo Ballard really on par with Aretha [[as Mary Wilson has suggested)? What about Kim Weston, Brenda Holloway or Barbara Randolph? Is Blinky just a run-of-the-mill R&B shouter? Certainly, Barbara McNair was a vocal firecracker but does she really rate with homegrown Motown talent? Tammi Terrell? Very interested to hear what true Motown connoisseurs have to say.

For the very brave among you, please feel free to rank your choices in numerical order