The thread's question is more interesting regarding only WTA titles, as any decent player can take an ITF if she really wanted to.
What is the highest rank:
1) Reached before winning a title?
2) Reached by a player who stayed titleless?
To the best of my knowledge, the answers are
1) Petrova #6 (maybe followed by Schiavone #11)
2) Kournikova #8
I'll greatly appreciate a top 5 (or 10) list to both.
Thanks to AnnaK_4ever
for his answer:
"Betty Stove was #5 without ever winning a WTA tour title, Kournikova was #8, Winnie Shaw was #10.
I believe they are the only top-tenners to have never won a title.
As for players who broke into top-10 before winning a title it's a tough question. The ones I know for sure are Graf (#3), Zvereva (#5), Rubin and Petrova (both #6), Dementieva (#9), Habsudova (#10)."
So that makes the list of highest ranks achieved with no WTA titles look like this (in parenthesis - first title won):
1) #3 Graf (Hilton Head, April 1986)
2) #5 Stove (never won a title)
2) #5 Zvereva (Brisbane 1990)
4) #6 Rubin (Linz 1997)
4) #6 Petrova (Linz 2005)
6) #8 Kournikova (never won a title)
7) #9 Dementieva (Amelia Island 2003)
8) #10 Shaw (never won a title)
8) #10 Habsudova (Pörtschach 1999)
10) #11 Schiavone (Bad Gastein 2007)