Valium would make the most sense, It has the longest half life of any benzo. I was on Xanax for 2 years. I am now cross tappering to Valium. Be sure to ask your doctor about cross tapper of benzos. Xanax is very addictive, I did not know I was addicted untill I switchted to Valium directly with no cross tapper....a couple of days latter....BAM XANAX withdraws. Not fun. Take a look at these links about benzos share and discuss them with your DR.
www.benzobuddies.org/benzodiazepine-with...methods/substitution
www.benzo.org.uk/manual/bzsched.htm
These links are sites to kick benzos, however in my case I was switching to a differnt benzo and found alot of the info relavent and helpful!