Thor: Ragnorok is going to be amazing!
Still no reviews on the quality of the 3D yet.
#1 IMAX With Laser - 3D or 2D
IMAX with Laser offers dramatically higher contrast than normal projectors. This means dark scenes where shadows wash out most details with normal projectors will show lots of detail when projected with Laser IMAX. Also, extremely bright things (like the green beams shooting out of the Death Star) can be shown much more intensely.
The picture will also expand up to the full 1.9 aspect ratio that the movie was filmed at because it is an IMAX theater.
You can find a list of Laser IMAX theaters here:
#2 Dolby Cinema - 2D only
Dolby Cinema has very high contrast just like Laser IMAX does, with the same outstanding advantages for bright colors and darker scenes.
Also, these theaters incorporate Dolby Atmos sound systems. These computerized surround sound systems can make sounds appear to come from any point in or around the theater (and make the apparent position of the sounds move throughout the theater to match the action on the screen).
There are some disadvantages though. Since it is not IMAX, the taller aspect ratio will not be displayed. The movie will be confined to the normal theater aspect ratio.
Also, while Dolby Cinema is capable of 3D, they almost always choose to produce only 2D versions of a movie.
Still, these theaters will be far superior to everything other than a Laser IMAX.
You can get a list of most Dolby Cinema locations here (it doesn't have the newest theaters though):
You can get the most up-to-date information (for the US at least) here, but getting it is slightly less straightforward.
After you select your location, click on "filter by: premium offerings" and select "dolby":
#3 Digital IMAX (liemax) - 3D or 2D
While no comparison to options #1 and #2 above, the dual IMAX projectors of a liemax theater will do 3D better than any theater besides that.
Plus you get the full 1.9 aspect ratio that the movie was filmed at.