First, I want to talk about the principal "Anti-Eremika" argument: Mikasa and Eren are siblings. Actually that's not a stupid argument, but I think it mainly comes from the fact that at the beginning we see them together in same house, so in everybody's mind they were siblings. It turned out that they are not related but it's difficult to change a first impression... I think a lot of people see them as siblings because they thought they were really blood related at the beginning.

So, first, Mikasa and Eren are not blood related. Everyone knows that (I think 🙄). After her parents' death, she lived with the Jäger. However that doesn't necessarily mean that she was adopted... Actually, she wasn't legally adopted because she still wears the Ackerman name. But, that's not important. The only thing we have to care about is: Does Mikasa consider the Jäger (especially Eren) as her family?
Remember that Mikasa has never referred to Carla and Grisha Jäger as mother or father. She said "Dr Jäger" and "your mother" (talking to Eren).
Also, don't forget that she was nine when she lost her parents. At that age, it's hard to consider other people as your new parents. Especially in 1 year... Therefore Eren and Mikasa weren't raised as siblings: because they met each other for the first time at the age of nine, and lived together for only one year! This is why I said that the storyline was misleading us: we got the impression that they always knew each other whereas they met just one year ago! Keep this in mind. 👉😊

However, that's true, she called Eren her family. Actually, Mikasa is the only person to say that Eren and her are family. Other characters don't see them as siblings. For example, Levi said that he is her "childhood friend" and "precious friend​.

Jean was jealous of Eren, and Ian called Eren her "boyfriend" (probably because of her extremely protective behavior towards him).

She blushed and she replied that he is family. At this moment of the story, we thought that Mikasa was considering Eren as her brother. Yes, even me 😂. But now, I think Mikasa's conception of family goes further than just considering someone as a member of your family. She doesn't say that Eren is her brother, but her family. That's a bit different. I think her "family" is just the people she loves and cares about, because she doesn't have a genetic family any longer. I can't proof that, but Mikasa considering Eren as her brother would go against all her behavior and what she says. Just read my other arguments and tell me after that if you still think she could consider Eren as her brother. 😉

Eren is the most important person on Earth for Mikasa. That's undeniable. Since the day he saved her, she always cared about him, protecting him has become an obsession for her. I hope you all have noticed this, because it's pretty obvious 😂 (cf: almost all Mikasa's scenes 😅).

We could say that she is just grateful for saving her, years ago. That's true, indeed, but there's something more. Mikasa said that as long as Eren is here, she has someplace she can return to.

She said that all she wants is to be at his side. (Episode 33, Chapter 45)

This is really revealing about Mikasa's feelings, and, honestly, don't you think it's something you only can tell about someone you love? Like I said before, there's nothing more important for her than Eren. She never wants to leave him. We are all ok with that, I hope.

There is also something funny that make me think she loves Eren: She can't bear the idea that he could in love with another girl. Remember when Eren didn't succeed to turn into a titan to fight Annie in episode 24...

Or when Eren was talking to Historia? (Chapter 70)

Yandere Mikasa confirmed 😂 This time this is not only to protect him, but there's a bit a jealousy...

Not to mention that Mikasa shows no interest in other guys (or girls)... (#jean4everalone)

Here comes my biggest argument: Chapter 50/Episode 37. When Eren didn't succeed to save Hannes, he cried and said he was useless. Then Mikasa told him "that's not true". This is pretty important: it means that she doesn't think he is useless, and she made him remember what he did for her (basically, why she loves him): she thanked him for being at her side, for teaching her how to live her life, and, the most important, for wrapping his scarf around her.

The scarf!  The ultimate symbol of the relationship between Eren and Mikasa. I believe that you all can easily understand what it represents. For Mikasa, it's something that reminds her Eren when he is not here (cf episode 33 for example). Eren giving her his scarf is the event that made her so grateful for him.  Permanently wearing the scarf that was his is not harmless... It's something that link her to him, that's why she never leaves it.
Some people say that the scarf stands for the Red String of Fate, a symbol of  unconditional​ love in traditional Chinese culture (also present in Japanese and Korean culture). The two people tied with this magic and invisible link (red but invisible, yes) would be connected by an unbreakable love, regardless of the distance, events and time, like soulmates (Thx Wikipedia 😂). However, this is not official, that's just an interesting theory. But even without adding this symbolism to the scarf, it still represents a extremely strong link between Eren and Mikasa.

Still in the chapter 50/episode 37, Mikasa thought they were going to die. Before this happened, it seems that she wanted to kiss Eren. I mean, nothing is sure, and when I read the manga for the first time I didn't think that... I thought this was just because of the reader's point of view, or something like that... However pictures made me doubt.

The bottom case, in the middle: this the moment when it seems that she is approaching her lips to kiss him (their faces were already super close in the previous case)... What do you think?

⬇Here is the anime scene ⬇

I didn't notice this the first time but... She was talking to him with a lot of emotions (even more emotional in anime), she was crying and smiling while thanking him, and then, she stopped talking. We saw her face approaching his slowly... And then Eren stood up. I analyzed this several times, and I'm still not sure, but it really seems that she was going to kiss him. I have to say that it's more obvious in the manga because of the case with a close-up on Mikasa's face, as if it is very close to Eren's. If this is true, no doubts can remain about Mikasa's feelings for Eren. And even if it's not...

I think that all these arguments (and others I didn't mention) are enough to say this: Yes, Mikasa definitely loves Eren.

But... what about him? We will see it in the next part...

This was my opinion about Mikasa's feelings for Eren. If you have any other arguments (against or for Mikasa's love), please give it in the comments, I would love to talk about it, and complete this part with it to make it as precise as possible 😉

This is probably going to be edited, to add details, more arguments and the  references, and maybe if there is a character's evolution revealed in a new manga chapter.