What I want to see is

Mirror's Edge 2
Fallout 4
More on Minecraft: Xbox One version
A nice look at Black Tusk's game
The announcement of a few new IP's
A new Conker game
Some more Halo info from that E3 trailer
More info about the Xbox One exclusive games that are already announced (Ryse, Forza, Quantum Break, etc)
A new Mass Effect game announcement.

Oh, no. Let that series rest a few years.

Crackdown 3

Fable MMO or at least some hint of whatever Lionhead is working on

something by Rare that isn't Kinect Sports Rivals

Ryse multiplayer, and improved combat

Anything Quantum, Break related

Xbox wise.

I want to see Quantum break gameplay

Dead Rising 3

Something from Rare that's not for Kinect

A new IP from Microsoft

2-3 years of rest is enough for me! 

New Mass Effect, Dante's Inferno 2 :p, The Witcher 2, some good Star Wars game, whatever realtime gameplay from Quantum Break & Black Tusk game + Crackdown 3.

So, what I want to see is:

That sexy new Black Tusk game
One or two new IP (the one from Rare )
Halo, Forza, Quantum Break...
Call of Duty; I'm actually excited about it on the Xbox One.
Dragon Age and Mass Effect
Will not happen but I would love to see some surprise announcement about Illimiroom available in December ahah! This would be such a day one purchase for me :)
Magic the Gathering online available on Xbox One! Zomg that would be great.

Rare's new IP vs Naughty Dog's new IP, things are going to get interesting indeed.(still hoping for a new Crash game).

anything that would make hardcore PS fans whine to there mummy.... i.e. an hostile IPO on SONY lol :P just kidding don't ban me :D

well I'd love to see some new Kinect games tapping in the improved capabilities of the sensor... hoping for a show floor demo with a full fledge 5.1 set up and Kinect voice control working fine in the heat of battle a la ME3

beside that I want to see new IPs, announcement of stuff like Halo5, ME4, fable 4, crackdown 3, mirror's edege 2, kameo 2, PGR , a bunch of nice F2P and MMOs

some more info on quantum break and the other exclu we haven't seen much about....

and some more info on XBL gold services and apps, maybe some more info also on the TV pass-through deployment outside of USA.... I will change ISP in the next 6 to 12 months to go with optic fiber I need to know if it will be tied to the ISPs or just the country or maybe basic functions won't even need anything and work out of the box... well basically more info on the non gaming part of the Box which is a major day one selling point for me.... if it was just for games I wouldn't even consider a day one purchase.... so I need to know more...

I really want to see a rare game that is not k sports. A banjo, conker or jetforce g.