I don’t know yet. It is still being written. Still, as ever, a work in progress. Is love of a craft a boon or a burden? That’s a trick question! Things can be both! I want to love my demo reel, yet the things that really excite me require… alot of technical know-how. Alot of technical know-how. I’m the guy who sneaks into the “restricted section” to read forbidden knowledge. Doesn’t mean I’ll understand it, but I’ll try. Again. And Again. And Again. And Again. … (Sorry about the spiders Australia ._.)
https://giphy.com/gifs/MXdUphiKGMnkWegWO4/html5
In the past, and in fact I think it was one of my very first posts here, I asked about “Demo Reel Scope”. My mindset, filled with enthusiasm (so you know it’s definitely me), was rigid from mistakes made from presumption of patterns. Still a creature of the environment I once inhabited. I wanted to know how BIG my demo reel “should be”. I thought there was a difference between a Demo Reel for Juniors vs those from Seniors. All in all, there isn’t. Yea there are knowledge gaps, and far more shipped games and such, but… such is life. Good work is good work, be it a small dust impact or some Alembic fluid sim with a multi-stage shader that interpolates some vector motion blended spawned procedural … compounding technical whoda-hada. 
Good work is good work. Knowing the difference is 50% of the reel right off the bat, though those numbers can very. Naughty Dogs take may be diffrent then Obsidian, or Bioware, or CD Red. What? You thought it was going to be simple? Some paint by numbers? And why oh why am I suddenly talking in the second person point of view!?!
At the heart of it all, It doesn’t matter WHAT it is. Chances are a person knows what they would like to make, and where (or what) they would like to work on.
All that is to say; What’s in my portfolio? Hopefully, its stuff I loved to make, and will love to show. And then… and then I think the rest will work its self out. If you get hired from stuff you loved to make, in theory, it will be where you work as well. 