I'm late to the conversation but from what I've seen, here are my views... (I haven't caught a lot of it mind)...
It seems both are as bad as each other - neither are squeaky clean.
Against Depp
Depp's past indiscretions seem to have been minimised by much of his supporters/the media. He smashed up a hotel room, brawled with paparazzi, allegedly smacked someone on a film set and his drug and alcohol abuse has been widely dismissed or minimised. Does that mean he was guilty of any offenses against Heard? No. But lets not make out this guy is a saint (not saying anyone is BTW). And "that message" saying he wanted to defile her burnt, dead body is hardly "bantz" either. It really shows the kind of individual he is.
He was said to have assaulted Heard on several occasions and his behaviours seem consistent with someone who may be an abuser.
Against Heard
She comes across as aloof, cold and arrogant and despite her best attempts at winning over the jury (and public) she hasn't been able to pull it off. Her approach has often seemed overly rehearsed.
There are some inconsistencies in her stories and this has been a bit issue for her. The make-up issue, accusations of violence against her ex partner, former assistant accused Heard of angry outbursts and spat at her. She also confessed in an audio recording that she had hit him.
But...
We need to remember that just because Heard (seemingly) didn't shed a tear in the stand doesn't mean she is acting or lying. Trauma is an extremely delicate and nuanced concept that is a full body response. Many trauma victims don't "show" emotions accurately; either through having blocked much of the trauma out or by learning that emotional expression = punishment. Unfortunately I suspect her legal team told her she had to "get the tears" and when she wasn't able to produce (probably due to a high pressure situation) it made her look disingenuous.
Also if her BPD diagnosis is to be believed it may well be that she simply isn't able to bring the appropriate emotions to her body language/facial expressions in the moment. This isn't uncommon for people with BPD - often what they feel and what they look like aren't congruent, making people feel ill-at-ease and distrustful.
Depp clearly has gone through the wringer in the relationship and probably has a huge number of issues himself. I do believe he genuinely wanted to escape the fights they engaged in, hence the frequent "running away" when faced with a confrontation. The fact his former wife and Kate Moss have both said he was never aggressive during their lengthy associations further lends credibility to his case. That said, he certainly has continued to control her in terms of bringing the case; he is giving the world the message "f_ with me and you will suffer". It shows the huge level of influence and power he has that people have turned against a woman (which is isn't all that common in these instances).
So...
I haven't watched enough of the trial to comment on the detail though I suspect this was a two way abusive relationship probably fuelled by Depp's drug and alcohol abuse and her emotional intensity. The whole thing sounds incredibly disordered and unhealthy. I won't go into body language stuff as I don't want to bore people though Heard in particular seemed very unusual at times.
Note: all allegations are based on news info! Don't sue me!