♡ Which one to buy?

I'm browsing on Sigmabeauty.com and I'm hesitating on which brush to buy. I already have the F80 in my cart right now which is $16. The thing is that if your total order prior to shipping is $30 or more, you get a complimentary gift and right now for October, the gift is a sample from the Brow Design Kit. So I need another brush for around $14 to get the subtotal of $30. So which one should I get among these? Please help :) :) :)

While writing this post, I was searching the blog at the same time and I thought that the gift was the Brow Design Kit but it was just a sample. Now I'm hesitating whether I should really buy now or wait for next month to see which gift you can get because I don't need another eyebrow shade or eyeshadow color. Yeah the eyebrow color can be used as eye shadow as well. So maybe I'll just wait for next month which is not so far away. Here is the one I am definitely going to take next month.

F80 - Flat Kabuki
Image Source: SigmaBeauty.com

Which sigma brush is your must-have brush? I want to know because I do not know which one to buy apart from the F80, and there are so many different, I can't choose.

P.S: I think I'm mistaken, the sample is not the complimentary gift anymore, I don't know what's the gift right now. Do you know, please please please tell me :)