My Heritage is the right place for Dylan, unless like many of us he becomes accustomed to the Geni World Tree and sees the utility and beauty of it.
I have a tree on Ancestry. I have a tree on Reunion on my home computer. I even have a small tree on My Heritage. The tree I add to and share with family is on Geni and I am quite satisfied, but I do download to my home computer periodically.
There are standalone trees on Geni but once you are connected to the World Tree, your public profiles (beyond 4th great grandparents) will be merged.
I realize that people join sites with expectations and pre-conceived notions but one's pre-conceived notions can land you in trouble.
The Geni concept is that share ancestors and in particular shared notable individuals like King John (whichever King John you mean) are managed by many people and are ideally curated. Anyone can contribute to the profile, although preferably in consultation with the Curator and managers. Starting a discussion thread and posting the URL of the profile is the best method.
Images are interesting. They are very subjective and as such people have strong opinions and are quite bothered by others' choices for their shared ancestors. I certainly understand. I have had exactly those strong opinions, but over time I have taught myself to relax because images ARE subjective. Wouldn't it be nice if I could see the image I thought best and you could see the image you thought best? That's not possible right now but there's no reason you can't start a discussion and have those who manage and care about the profile all weigh in.
As for your bio being overwritten by the merge, someone else needs to comment on what happened. I suspect it's because the profile was locked, but since you haven't posted a URL I can't check it out. I agree with you that that is not optimal. In many (most?) instances, what I have seen is that the About Mes from the merged profiles aggregate with dotted lines between them.
Since I assume King John is curated, he should have a good bio. I am sorry yours was deleted. There's no reason you could not propose to replace the "bio" that is there or add to it. That's called collaborative genealogy.