Brock Lesnar, Finn Bálor, Matt Hardy, Seth Rollins, Jason Jordan, and Roman Reigns. I'm assuming Cesaro and Sheamus win back the titles at the Royal Rumble and that Miz will win back his title at the rumble. Lesnar will win by the skin of his teeth - or perhaps due to Jordan sabotaging Roman - and will ultimately face Roman at WrestleMania.
I can't say I have much confidence in a women's chamber being very good, but it wouldn't be surprising to see WWE go for it since their big thing for the past year was testing women out in various stipulations they normally never wrestled in. I'd be more interested in the cruiserweights getting a chamber match and being let off the leash to go do whatever they want. That would be a great opener to the PPV. Regardless, I'm seeing Asuka, Alexa Bliss, Nia Jax, Sasha Banks, and Absolution being in the chamber.