I do all my work in OS X, and wanted to share information about the hex editors I use, in the hopes that it will help other ROM hacking Mac users. There are four main hex editors available for OS X. Here they are, rated (in my opinion) from best to worst:

1. 0xED - I think this is editor has the best interface and is the easiest to use. It's fast, and includes an ASCII table window if you need it. There are two small areas at the top of each window to jump to an offset or do a find, which are nice to store values that you want to jump back to frequently. You can also open the "Jump to offset" and "Find" windows, and store different values from the areas at the top of the windows. It has options to extend/shrink selections and move selections. There is a plug-in architecture, but you have to install the OS X Developer Tools, which I haven't. I don't quite know how they work, but I believe it might be possible to create plug-ins to use like character tables. The only downside to 0xED is that I've noticed a bug when copying and then undoing large blocks of hex data. Sometimes when you undo it erases the data rather than undos it. It hasn't happened that frequently to me, but as always, keep backup copies of what you're working on.

2. HexEdit - The interface on this editor is not as clean as 0xED or Hex Fiend. The window can't be extended more than 16 bytes wide, and the position display is always 8 characters wide. (These two things alone drive me crazy.) The dialogue boxes are a little clunky, too. The nice thing about this editor is that it has a compare feature, which 0xED lacks. Unfortunately, even that is a little difficult to use. You have to search through differences one-by-one, it doesn't highlight all of them for you.

3. Hex Fiend - This is also a fast editor with a clean interface (though scrolling seems to be a little slow). The interface is actually a little too clean for my tastes. Although there is a extend/shrink selection option, there is no "jump to offset" option, and it only displays the current offset in decimal. I also seem to remember it quitting on me a few times when I was first using it. The only reason I keep this editor around is that its Find dialogue automatically puts a space between bytes when you enter data. 0xED copies and pastes data as a single line of hex values (which I prefer, actually), but when copying to a text file for later reference, spacing the bytes out is a handy feature to have.

4. PeekIt - This is by far the ugliest and most convoluted editor of the four. It does have the most options, such as for notes and to create a changes file, but even changing the hex data is a hassle. You have to click on where you want it, enter the new values in a little box, and click "Apply." It also doesn't seem to be very stable. In fact, just testing it now made it quit on me. The only reason I mention it is because it has a compare feature with highlighting, which is useful. If you need that keep a copy, otherwise, don't bother.

I use 0xED for everything except comparisons. Since it wasn't built for ROM hacking, it doesn't support tables or any of the fancy things that other editors do, but none of those editors work for OS X anyway. If anyone knows of a better editor than these four, please let me know. In my estimation, 0xED is by far the best hex editor available for OS X at this time.