Should I use Plain TeX or LaTeX?
There’s no straightforward answer to this question. Many people swear
by Plain TeX, and produce highly respectable documents using it
(Knuth is an example of this, of course). But equally, many people
are happy to let someone else take the design decisions for them,
accepting a small loss of flexibility in exchange for a saving of
brain power.
The arguments around this topic can provoke huge amounts of noise and
heat, without offering much by way of light; your best bet is to find
out what those around you are using, and to go with the crowd. Later
on, you can always switch your allegiance; don’t bother about it.
If you are preparing a manuscript for a publisher or journal, ask them
what markup they want before you
develop your own; many big publishers have developed their own
(La)TeX styles for journals and books, and insist that authors stick
closely to their markup.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=plainvltx