oh..
dunno about my favourite, but these are the most used:
Dopus Magellan
Hippo Player
Protracker 3.18
XCopyPRO was the most used app back when I had a 500 :-)
Disksalv is nice when I accidently delete something
Aegis Audiomaster for editing samples
FastView for viewing jpg's
AmiCDFS
reqtools.library :-)
..and lots more I couldn't live without
