No way does Venus deserve a top 10 ranking all time. Top 20 for sure, top 15 maybe but probably a stretch. Venus ranks far below Graf, Court, Navratilova, Evert, Lenglen, Wills, King, Serena, Seles, Connolly, and also should be behind Goolagong, Bueno, Henin, and possibly even Gibson, Hart, and Brough. Venus has won only 7 slam titles in the era of equality of all 4 slams. She has only won at 2 of the 4 slam venues, no titles at the Australian or French Opens, and only 1 final at each. She has never ended a year ranked #1. And she has spent what, all of 11 weeks at #1 in an era that has seen a succession of clown #1s. And before suggesting her stats dont reflect her overall ability she has basically equal head to heads with Hingis and Davenport which hardly suggests historic level ability.
Seles ranks over Venus all time easily, it would be foolish to suggest Venus's Wimbledon record alone puts her above Seles and ignoring all the other many holes in Venus's career, in addition to atleast some slight consideration to the unusual circumstances Seles faced. Venus is the better grass court player of the two by far, but not the better player overall. Even Henin who btw I cant stand rates atleast on par with Venus, and quite possibly ahead. Seles is at a clearly higher level than both though.
The Williams should also not be potrayed together in a historical light. Serena is light years beyond Venus. As I mentioned Venus isnt even the 2nd best player of her era probably.