Stuff I want:

• Focused on interactions of a group of friends against some mystery or villain or both
  
• The magic system has to be very similar to canon (Somewhat poetic in nature, requires significant effort to master etc)
• Characters maintain their core personalities
• Doesn't have to be Harry as MC

Stuff I don't want:

• Bashing
• Excessive angst
• Muggles superior to wizards (either technologically or culturally)
• Massive changes in world-building or tone such as enembee or joe's stuff

 

You might try What You Leave Behind by Newcomb. It's very good and has most/all of those things.

 

Yeah, now that I think about it that is a perfect recommendation, thanks. Already read it though.

Well these ones are more like preferences as long as everything is well-written and mostly self-consistent:

• Characters maintain their core personalities
• The magic system has to be very similar to canon
• No muggles being superior to wizards
• No massive changes in world-building or tone

 

Yeah, well that is the problem: most stuff isn't well-written or self-consistent. And beyond that requirement, I'd say most of the better writers in the Harry Potter fandom write an older Harry, usually starting in fourth year or later. This makes for them to get to where the real(?) plot is, while also allowing them to avoid having to write really young characters which are hard to work with.

 

I've not read it in years, butFugitives of Azkabanby Bajab comes to mind, as something that would maybe satisfy your requirements. His other stories are more well-known but this has stayed in my mind for some reason.

 

Have you had any luck so far?

If you haven’t read it, Hunting the Grim by Sophprosyne/@Plothole is pretty good. If I recall correctly, it fits most of your requirements. It felt like reading a story in an alternate universe where Rowling made all of PoA as dark and bleak as some parts of GoF are. It’s decidedly not a happy story, but I enjoyed it a lot.

 

Slight necro, being 2 months and all, but Harry Potter and the Untitled Tome seems have a lot of what you're looking for. Currently in Year 2, and has a far larger Wizarding World, but keeps the whimsical tone of canon.

Pretty sure it's also in the WBA

 

I'm a bit late to this thread, but The Mind Arts by Wu Gang seems to be a story that meets your criteria to an extent.

I guess this story is kind of like one of those really crappy clichéd ones where all of the eleven-year olds act and talk like they''re fifty, but Harry's basically the only character that does in this story, and it's actually pretty interesting how that influences the interactions between him and other characters.

I'm not exactly sure if the magic in this story really meets your requirements, as Harry is basically a prodigy in that particular subject, but this story does have a concept of occlumency that's not actually absolute crap, and that just makes me like it so much more than I would've.

This is a difficult criterion to meet, since most AUs don't like to preserve the characterisations of canon, and this story uses mostly blank-slate characters to fill up the cast.

This story is a filled with a bit of angst, but most of that is towards the beginning, with Harry being neglected by the Dursleys, not having any friends, etc. But that passes by relatively quickly and the story eventually becomes the exciting world of wonder usually associated with Harry Potter.

TL;DR
The Mind Arts by Wu Gang meets your list of criteria the majority of the time.