I have tried all extensively (except ConTeXt), what I can tell you is that I now use LuaLateX, because it's the natural successor to the other implementations, which have all a really hard time with unicode, ie. with "→" and many other unicode characters. I know about different hacks like embedding a pdf document with the required symbols etc. but that's just reflecting how ignorant the LaTeX architecture is. The algorithms built-in may be clever, but the actual code-base and annual release-cycle is archaic and unmaintainable. The cross-dependencies are so deep, that updating one small package could break anything anytime. Spaghetti-Code Deluxe. Guess why no distribution ships "tlmgr" - the TeX package-manager.

I'm thankful for anything that helps to free us from the *TeX compilers. It's surely hyped too much. Do you believe me when I say that just because you wrote a document with LaTeX, it isn't auto-magically typographically perfect? Look for PDF Documents compiled with LaTeX, many of them have really ugly Typography, because people love to customize things to their own likings and many LaTeX templates even force ugly Typography on their users.