Individual Files:
Nero
Protected CDs:
Alcohol 120%
Audio Disks:
Alcohol will do a good job of these too - if it's not protected then you can use pretty much any software for copying them
For mastering audio disks I personnally use Winoncd and also Nero.
Ripping Isos
Alcohol can rip to a huge amount of different file formats - brilliant
Burning Isos
Again Alcohol mops up here as it supports a lot of things and gets the job done.
Visit the Clone CD site
www.elby.ch and check out it's Supported writers list. If the burner has "two-sheep" in the EFM column, then thats a burner you should consider getting as it can copy Safedisk easily. But also make sure it can read/write subchannel data and supports RAW-DAO-96
Good writers include, Lite-on's, and some LG's (there are many more).