I love almost all of the actresses listed. But the more I watch Buffy, the more talented I find SMG to be. She's amazing.

I think she's brilliant. She's been nominated for an academy award, and I think two golden globes, right? (for Pride & Prejudice and Atonement)
She seems very serious about her work.

Thora can play pretty much any part - outcast, psycho, even the subject of a Lifetime movie. ;) I also considered adding either Liv Tyler or Tawny Cypress, as they're both great... but when in doubt, I stick with Thora. =P

I LOVE HER!

Alyson is the best!

I loved her in Camp Rock

nosemuffin, i totally agree with you! SMG is really good in buffy and in cruel intentions and theres so much more lol my order for the ones listed would be

SMG
keira knightley
rachel mcadams
sophia bush
anne hathaway
alyson hannigan

no offense testcamp but demi lovato has only been in like one thing, how do you know shes a versatile actress and can act in diverse roles?

I adore Keria, Also Kristen Stewart is an amazing actress for her age.

i <3 sarah!!she is one of my favorite actresses!!!!!!!!
sohpia bush and rachel bilson are good too

She has so much talent

Smg is amazing but i also think Sophia Bush is really talented

I would have to say Rachel, she is brilliant in all her acting.

She got the Oscar, didn't she?

I like many of the actresses on here, but Period Films are my favorite and Keira is wonderful in them! :)

Also, I'm not sure if she's my very favorite, but I cannot possibly think of all the actresses (even under 40) that I like, so, out of these, she's my favorite.

many of them, but she's my fave.

There are a few. Scarlett Johansson, Cate Blanchett, who is 39, I think, I checked ;), Gwyneth Paltrow, and Keira is growing on me <3
I could have picked any of these.

Almost all of the other ones!

Blake, Sarah, Sophia, Rachel, Keira

It's nauseating how underrated she is!

also Reese and Sophia.