CotEditor

The Regex 正規表式 used is CUI regular expression engine (Important changes on CotEditor 4.2 - CotEditor. Never heard of it.

Quick verdict: 3.5 stars

Pros

Rare treasure: amazed to discover support for \p{Han}, \p{P}, and the like.

Cons

Large files: Freezes or crashes, or grinds to a halt, when opening large text files (~ > 100MB), something EmEditor would handle with grace and ease. Even Sublime Text (Mac) will do.
Can't handle deleting duplicates in 800K-line files. Can't hold a candle to EmEditor

I have renewed unmitigated respect for EmEditor, a powerful editor that handles large text files with ease and grace. I am talking about a 500MB text file with 3.2 million lines and it still sorted it and deleted duplicates in it in a few seconds. In comparison, CotEditor on Mac, despite my delight in discovering its support for Unicode script/code block regex like \p{Han}, can't even handle one quarter of that (800K lines) without hanging indefinitely. It's such a pity that EmEditor, my favorite text editor bar none since I found it in 2000s, is Windows-only.

No plan to support search and replace in opened files or in multiple files under a directory, not to mention recursively.

(Also, I hereby confirm that unfortunately CotEditor does not support regex conditionals.)

Character class subtraction (regex) is not available.

Quick verdict: 3.5 stars

Pros

Cons

No plan to support search and replace in opened files or in multiple files under a directory, not to mention recursively.