The ones I find myself going back to (depending on the task)
IA Writer
WriteRoom
Textastic
enso Writer
Notebook
iA Writer and Writeroom are easy to use on any other computer because of their sync. Notebook is cool because of Sync also- but it's only available for Mac, so that cuts out using my desktop, only my laptop. I love enso, but it's sync to Dropbox isn't automatic. Same with Textastic- it would be the one to beat with code editing also, other than the fact that the sync is manual.
Just like on Windows, I'm addicted to editors, so the ones I've tried include:
My Writing Nook
Notebooks
Textastic
Noteshelf
Notes Plus
iA Writer
enso Writer
Essay
Writing Kit
Note & Share
WriteRoom
Textkraft EN
CleanWriter
Circus Ponies Notebook
Evernote
Noterize
Penultimate
MobileNoter
Notability
Simplenote
PlainText
WritePad
Nimbus Plus
Nebulous Notes
There are some other code specific ones, but I don't think that's what you're looking for. I've been looking at trying Write 2, specifically because it lets you use your iPhone as a keyboard which I think is cool
If I may ask, what did you think of Textilus?