Emacs is still the best for most of that. Text display works most of the time (although it sucks), there are intelligent modes that aren't a pile of half-correc

Emacs is still the best for most of that. Text display works most of the time (although it sucks), there are intelligent modes that aren't a pile of half-correct regex hacks (semantic, most of the modes for the Lisp family), and the base is fairly stable (some of the packages may not be). OTOH, it could be better. If you don't mind the lack of extensions, and are willing to write your own, you may wish to try some of the other emacsen associated with the lisps. Hemlock is CL-based, so likely faster than Emacs, and Edwin and Guile-Emacs are both based on Schemes (edwin is MIT Scheme, Guile Emacs is... Guile). They still suck at some stuff, though, and they don't have the massive plugin ecosystem.