Marcusboy:

Basic earn rates for citi pm and cx elite are the same (local $8/mile, overseas $4/mile)

Only differences are citi pm will be a lot more accepted as it is a visa. But beware citi does not count china and Macau as overseas for points earning purposes (despite collecting foreign currency translation fees)

Citi prestige has a better local earn rate than either of them - $6/mile. It will still have similar acceptance like citi pm cos it's mastercard