Who did you pick? And why?

Lol, you do know i did Ander's romance first? It was really creepy, saying he'd drown in blood to save my Hawke. Now, that was creepy. If you do Ander's friendship romance, your allowing Justice to take away something away from Ander's (common sense, control, etc), and with Rivalmance, at least Ander's has some measure of control over Justice, who was slowly taking over his mind when your doing Frienshipping. 

This is simple not true. The rivalry with Hawke AND Justice will kill him slowly and cruelly. He will lost the control over his mind, and will lose himself and finally die. This is the end of rivalry. On the friendship path he have don't lose the controll over himself. Do you think, he don't wanted to do, what he done? But yes. He wanted. 

Yes. Clearly. Justice don't want to take Anders' mind and memories, and he just appear when he feel some danger. I understand, why rivalHawke attack Justice (because s/he think, this is unnatural and dangerous), but I think, this only makes things worse, not better.
He have chance for a longer and more calm life with harmony with Justice in friendship. In rivalry he will fear from Justice, and Justice will not trust him. Yes, not excluded, that in both case he will lost himself, sometime, and Hawke will forced to kill him. But in friendship this is less of a chance.

Yeah, so I suppose doing Rivalry doesn't matter much to the current situation. And btw, it is creepy. It realllyyyy is, you look through from a normal non-fan perspective, his aggressiveness towards Hawke is alarming, as well as him falling in love with Hawke. That's creepy in it's self.... Meh, some can be attracted to aggressiveness, but I'm not...

This is the point. The rivalry don't change anything, only torture him. 
When he agressive with Hawke on friendship path? I can't remember that moment.

My Hawkes agreed with him, In Kirkwall doesn't exist the peaceful solution.
This sentence exist in rivalry too. I checked on YouTube. Then: why the friendship path is creepier, than the rivalry?

Yes, we can say. He is not an easy guy. Isabela much more better to you.
You don't rivalry with Anders yet?

Yes, but Isabela better to you, than Anders, because you likes Isabela, and Anders annoy you, or not?
On rivalry path he show more about his work, and Justice, as I saw in video, but Anders is sadder than on friendship pat. Honestly, I don't like. I think, they have some chance a happy end at mage side, but this is simple sad to me. 

Okay, I need to put my thoughts into this: why is Anders' declaration of 'I'll drown us all in blood to keep you safe' any creepier than being with a guy whose MO is to rip people's hearts out whenever he's protecting Hawke? And I say that even though I like said magical-fisting guy to bits.

And let's not forget two things. Another of our companions had a spirit inside them and yet she didn't seem to lose herself because they were at peace with one another. Anders is also the first to admit in the first act that he often loses control because of *his* anger, not the spirit's.

The question is, how *you*, as the player, perceive the situation, and the answer is given much later by Solas. If you follow the Friendship path, you perceive the spirit within Anders as good, as Justice. If you go Rivalry path, you perceive it as a demon and wrong, thus Vengeance. And so the spirit will act accordingly. That is, Anders is still himself in Friendship because they aren't warring, but in Rivalry, he's taken over.

Yes. I wrote about this scene, what you linked here. This was a danger from his viewpoint: Hawke wanted to convince Anders, that the peaceful solution exist, and Anders became uncertain. (We know, this is not right, no peaceful solution exist in Kirkwall, Anders was right in this scene, just Hawke hadn't understand him.)
This scene is creepy. In rivalry I like better, than Hawke don't help Anders in to distract Elthina. I don't like, when hes mind disintegrate, and start blame only Justice. But this is only me, I know, not a popular opinion.

Sorry, I hadn't noticed you mentioning the second scene. But your initial argument was that Justice is Anders and that it was only danger that fuels Justices takeovers.

The only danger in that scene is that Anders might not do what JUSTICE wants. And my statement was that Justice is too possessive to be a mere spirit.