You should get both for the bonuses. Here is the quick comparison:
AMEX
6 pts/$ - Hilton
6 pts/$ - grocery, drugstores, gas, wireless, cable TV, and ISP
3 pts/$ - Everything else
CITI
6 pts/$ - Hilton
3 pts/$ - grocery, drugstores, gas
2 pts/$ - Everything else
I personally only use the AMEX version, but its handy to have the visa version in case the grocery store you go to (such as asian markets) don't take AMEX.
Last edited by cyin; Jan 21, 2012 at 6:44 pm