For me Wozniacki doesn't belong on this list. If she does, then there's numerous others who I'd put there too, and above her (Dementieva, Ivanovic, Safina, Stephens, Pliskova, I might even put Swiatek over her already). Some of them were just not lucky enough to have Halep outchoke them in the third set of a final. Her weeks at number 1 mean nothing to me in that era. She's more comparable to me with those on a lower level - Jankovic, Stosur, the likes of Zvonareva, Aga, maybe even Kenin and Bartoli

(I'm president of the I Hate Caro Club. Sue me.)
12. Li Na - Glad to see her here. She's great, and has become way too little remembered. I just think her run at the top was over too little a time, and unlike most others here she only really has success on two surfaces instead of all three. Plus her run on top really coincides with the lamest period in the history of womens tennis. If she'd done a little more earlier she'd likely be a fair bit higher.
11. Kuznetsova - I hate putting her this low, but like Li, her grass success is relatively minimal. Her longevity and the badassness of her game makes me want to put her higher (and her longevity is the main reason I rank her above Li), as does her pretty great run to the Roland Garros final in 06, but her mental midgetry rearing its head so many times over the years keeps me from doing so.
10. Osaka - She has literally never won a title anywhere other than a hard court. She is incredible on hard courts, obviously, and that's why I put her over the two below, but the total lack of success anywhere else keeps her this low.
09. Barty - Her Wimbledon win was huge in building my estimation of her (no way she gets higher than Osaka without it) but her comparative struggles on hard court keep her from climbing any higher yet. That I think the best is probably yet to come allows me to give her the benefit of the doubt I probably wouldn't give Osaka.
08. Muguruza - She is the darling of my heart, and her top level is totally above others on this list I rank higher, but she's proven far too erratic even on the surfaces she's proven domination on. She and Ash are pretty close for me, I've just seen way more top level Garbi at this point, and making that final in Australia helps.
07. Kvitova - This might be controversial to many, but I think her exploits off of grass are pretty underrated. I got a lot of love for the longevity of her success, and her semi runs at Roland Garros/trio of titles in Madrid just blow my mind.
06. Halep -That year run she had from RG18 to W19 totally transformed my opinion of her. Before that she'd have been rock bottom of this list, but those two wins coupled with her consistency, and her being one of the few women on this list to be in the Major Semi Final Club totally rockets her up to here.
05. Azarenka - I used to hate her so much in her early years on top, but in this era of losers I've come to respect her fight so much. She's never won on grass, but the fact that in ALL 4 of her runs to the QF/SF of Wimbledon she has been beaten only by the eventual champion makes me think most highly of her. She's not that much lesser than Osaka on a hard court, and yet so much better everywhere else.
04. Kerber - Another one I used to HATE, but god she's so good. Her relative lack of success on red clay makes me think I'm being generous ranking her this high, but then I think of the many incredible matches over the years she's been a part of, and come around. Hope her mini comeback the second half of this year leads to good things ahead, but even if it doesn't... None of the ladies below her have won 3 out of the 4 majors.
03. Clijsters - Unlike Azarenka, her four runs to the QF/SF of Wimbledon see her beaten by the runner up every time

Still, multiple titles on all FOUR surfaces carry her higher, as does having played multiple finals at 3 of the 4 majors. She was always the also ran (along with Mauresmo) of that golden era, so I'm glad she got to come back and have that second run, pad the resume, and show just how lame that later era was.
02. Sharapova - Meldonium, schmeldonium. It was legal when she did everything that gets her this high on the list. How good she was 04-08 before she even hit 21 was incredible. I know successful teenagers in womens tennis are nothing to write home about, but not many of them wrap up three of the four majors before they hit legal drinking age, and not many of them have their serves compared to Sampras.
Her serve coupled with her icy mentality made her a rare thing as womens tennis sank into sadness, and that when she had the surgery that robbed her of that serve, and made her into a double fault machine, the fact that this self confessed cow on ice won TWO Roland Garros titles will never not blow my mind. The world took her greatest weapon from her, so she won the major she didn't really need one for. If that's not badass nothing is. She absolutely ended up in Serena's pocket, but that's the only thing I hold against her, and the career slam makes up for it.
01. Watch the last 3 matches of USO07 and try arguing it (Venus I think is the only one in the whole tournament who managed to avoid being fed either a bagel or a breadstick). Watch her be basically unplayable on clay for 5 years. Not even close. Venus and Serena being basically unbeatable on grass for a few years there is all that keeps her from being
undeniably in the all time great conversation.