I've been through
* evernote - slow and buggy UX, properietary format
* emacs org mode - good but you need buy in to org format, user experience across devices e.g. mobile not so good)
* quiver - pretty good, markdown format, but lacking android support
* git + markdown files - ok, but a bit finicky, again annoying across devices
* joplin - pretty good, has mobile support, has markdown etc
* nVault - lightning fast, no mobile support
I saw a thread on HN recently talking about a similar topic and someone mentioned TiddlyWiki which seems promising, I'll investigate it soon, although I suspect I'll probably jump when the next thing comes along.
Luckily most of my 'wiki' is in markdown format so it's fairly portable, I just want something that
* is easily accessible across devices
* supports markdown (+ rendering)
* supports inline LaTeX (e.g. $$x = 5 + y$$)
* renderer should support inline images
* good search capability