I am on AmigaOS 4 and my top 3 utilities are:
1. CygnusEd - Bought the latest PPC version. It's the best. By creating macros I automate much of the work that would need hours to do, including translations from one language to another.
2. DirOpus 4 - copy, delete, archive, lha, zip, lzx, move, examine, preview, comment, protect, edit and all the other stuff I do with my files.
3. IBrowse - I surf the Internet with it daily. Including Amiga.org. I use OWB as well, but more I work with IBrowse because it is faster and I turn off the graphics loading --> even faster.