There are questions on TeX.sX already about what the differences between LuaLaTeX and XeLaTeX are (Differences between LuaTeX, ConTeXt and XeTeX), what one should be keep in mind when going from XeLaTeX to LuaLaTeX (Considerations when migrating from XeTeX to LuaTeX?), and how they typically differ in their preambles (Frequently loaded packages: Differences between XeLaTeX and LuaLaTeX).
From the perspective of an end user, however, I've yet to see any reason for why one should switch from XeLaTeX to LuaLaTeX. That is, I have read facts like LuaLaTeX using the Lua scripting engine, but that is not relevant to an end user like me who has no idea what that entails.
Yet I've noticed that most of the cool kids here on TeX.sX seem to prefer LuaLaTeX over XeLaTex, and I'm curious what those reasons are, and more specifically, if they apply to "normal" end users like myself.
To give LuaLaTeX a try, I recompiled an old short handout of mine in LuaLaTex, and they mostly looked exactly the same. Where they differed, however, XeLaTeX clearly gave the better results. Below are some examples I found in my handout:
XeLaTeX:
LuaLaTeX:
\documentclass{article}
\usepackage{fontspec}
\setmainfont
[
Path = C:/Windows/Fonts/,
Extension = .otf,
UprightFont = LinLibertine_R,
BoldFont = LinLibertine_RZ,
ItalicFont = LinLibertine_RI,
BoldItalicFont = LinLibertine_RZI
]{libertine}
\begin{document}
mak\textbf{\underline{a}}t
\textit{wund\textbf{\underline{V\char"0306}}de}
\textit{*wund\textbf{\underline{\char"014D}}d\char"0113}
\end{document}
In the second and third word, LuaLaTeX adds more white space before the underlined italicized boldfaced characters. In my view, it adds too much. Notice, however, that it does not add any extra white space in the first word, where the character is not italicized.
In the second word, XeLaTeX handles the placement of the combining breve character well, but LuaLaTeX does not. This is potentially a worry, since I normally use a lot of combining characters in my documents (this being the only example in my handout).
If anything, I only see reasons to stick to XeLaTeX for the moment, but I am still curious if there are advantages to LuaLaTeX over XeLaTeX that could potentially override the disadvantages I've identified above.
lualatexwith Brill, DejaVu, Heuristica, and Source Sans Pro, all of which have themkmkfeature (Junicode also has it, but the output is ugly).mark(mkmkis for aligning diacritics to other diacritics)? So the question is why\textit{\textbf{V\char"0306}}gives a good result withXeLaTeX, but not withLuaLaTeX.lualatexhave both themarkand themkmkfeature. I don’t know which is responsible for the good result (I’ve also seen some fonts with anabvmfeature, and I’ve never tried to work out how font designers interpret each of these). But at least it’s clear that the differences betweenxetexandluatexaren’t the only factor; the font also plays a role.