I didn't choose Chosen because it only matched at start of words.
Yeah, that bothered me at first, but you can set "search_contains: true" to make it search the middle of words (and allow spaces).
And I only played with Select2 enough to hit one major quirk - it doesn't keep selected position once I start filtering, even if the selected item would still be a possible option. That made me a sadface.
On small displays, it sometimes decides to dropup instead of dropdown. The fact that it drives me crazy aside, that means that it'll sometimes clip the search area and top element.
Chosen doesn't do that, but will extend the page you're in past the visible area (adding a scroll bar) if it needs room for the select, which is kind of weird. That's actually what I think I might be able to fix with more tinkering... or just ignore and call good, because it's not gamebreaking and is probably less annoying than manually searching in any case.
Well, I can always just keep it as a GM script and enable it where I want. Pro: works for me. Con: doesn't work for anybody else.
Yeah, it'd be a nice feature. I like it myself, but also work on a teeny laptop, so am very aware of when stuff doesn't work well on small displays.