Which is better? XD or IMAX? for those who go to the movie theater a lot, which is of better quality?

XD or IMAX? and is it true that XD is solely exclusive to Cinemark
Theaters only? or is it available to all Movie Theater Businesses such
as AMC, Regal's, Edwards, etc.?
How do you compare them? what are the Pro's and Con's of XD and IMAX?